Use mod vendor for vendored directory (backwards compatible)

vendor/github.com/spf13/cast/.gitignore

@@ -0,0 +1,25 @@
+# Compiled Object files, Static and Dynamic libs (Shared Objects)
+*.o
+*.a
+*.so
+
+# Folders
+_obj
+_test
+
+# Architecture specific extensions/prefixes
+*.[568vq]
+[568vq].out
+
+*.cgo1.go
+*.cgo2.c
+_cgo_defun.c
+_cgo_gotypes.go
+_cgo_export.*
+
+_testmain.go
+
+*.exe
+*.test
+
+*.bench

vendor/github.com/spf13/cast/.travis.yml

@@ -0,0 +1,14 @@
+language: go
+sudo: required
+go:
+  - 1.7.5
+  - 1.8
+  - tip
+os:
+  - linux
+matrix:
+  allow_failures:
+    - go: tip
+  fast_finish: true
+script:
+  - make check

vendor/github.com/spf13/cast/Makefile

@@ -0,0 +1,38 @@
+# A Self-Documenting Makefile: http://marmelab.com/blog/2016/02/29/auto-documented-makefile.html
+
+.PHONY: check fmt lint test test-race vet test-cover-html help
+.DEFAULT_GOAL := help
+
+check: test-race fmt vet lint ## Run tests and linters
+
+test: ## Run tests
+	go test ./...
+
+test-race: ## Run tests with race detector
+	go test -race ./...
+
+fmt: ## Run gofmt linter
+	@for d in `go list` ; do \
+		if [ "`gofmt -l -s $$GOPATH/src/$$d | tee /dev/stderr`" ]; then \
+			echo "^ improperly formatted go files" && echo && exit 1; \
+		fi \
+	done
+
+lint: ## Run golint linter
+	@for d in `go list` ; do \
+		if [ "`golint $$d | tee /dev/stderr`" ]; then \
+			echo "^ golint errors!" && echo && exit 1; \
+		fi \
+	done
+
+vet: ## Run go vet linter
+	@if [ "`go vet | tee /dev/stderr`" ]; then \
+		echo "^ go vet errors!" && echo && exit 1; \
+	fi
+
+test-cover-html: ## Generate test coverage report
+	go test -coverprofile=coverage.out -covermode=count
+	go tool cover -func=coverage.out
+
+help:
+	@grep -E '^[a-zA-Z0-9_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'

vendor/github.com/spf13/cast/README.md

@@ -0,0 +1,75 @@
+cast
+====
+[![GoDoc](https://godoc.org/github.com/spf13/cast?status.svg)](https://godoc.org/github.com/spf13/cast)
+[![Build Status](https://api.travis-ci.org/spf13/cast.svg?branch=master)](https://travis-ci.org/spf13/cast)
+[![Go Report Card](https://goreportcard.com/badge/github.com/spf13/cast)](https://goreportcard.com/report/github.com/spf13/cast)
+
+Easy and safe casting from one type to another in Go
+
+Don’t Panic! ... Cast
+
+## What is Cast?
+
+Cast is a library to convert between different go types in a consistent and easy way.
+
+Cast provides simple functions to easily convert a number to a string, an
+interface into a bool, etc. Cast does this intelligently when an obvious
+conversion is possible. It doesn’t make any attempts to guess what you meant,
+for example you can only convert a string to an int when it is a string
+representation of an int such as “8”. Cast was developed for use in
+[Hugo](http://hugo.spf13.com), a website engine which uses YAML, TOML or JSON
+for meta data.
+
+## Why use Cast?
+
+When working with dynamic data in Go you often need to cast or convert the data
+from one type into another. Cast goes beyond just using type assertion (though
+it uses that when possible) to provide a very straightforward and convenient
+library.
+
+If you are working with interfaces to handle things like dynamic content
+you’ll need an easy way to convert an interface into a given type. This
+is the library for you.
+
+If you are taking in data from YAML, TOML or JSON or other formats which lack
+full types, then Cast is the library for you.
+
+## Usage
+
+Cast provides a handful of To_____ methods. These methods will always return
+the desired type. **If input is provided that will not convert to that type, the
+0 or nil value for that type will be returned**.
+
+Cast also provides identical methods To_____E. These return the same result as
+the To_____ methods, plus an additional error which tells you if it successfully
+converted. Using these methods you can tell the difference between when the
+input matched the zero value or when the conversion failed and the zero value
+was returned.
+
+The following examples are merely a sample of what is available. Please review
+the code for a complete set.
+
+### Example ‘ToString’:
+
+    cast.ToString("mayonegg")         // "mayonegg"
+    cast.ToString(8)                  // "8"
+    cast.ToString(8.31)               // "8.31"
+    cast.ToString([]byte("one time")) // "one time"
+    cast.ToString(nil)                // ""
+
+	var foo interface{} = "one more time"
+    cast.ToString(foo)                // "one more time"
+
+
+### Example ‘ToInt’:
+
+    cast.ToInt(8)                  // 8
+    cast.ToInt(8.31)               // 8
+    cast.ToInt("8")                // 8
+    cast.ToInt(true)               // 1
+    cast.ToInt(false)              // 0
+
+	var eight interface{} = 8
+    cast.ToInt(eight)              // 8
+    cast.ToInt(nil)                // 0
+