Add initial Keybase Chat support (#877)

* initial work on native keybase bridging

* Hopefully make a functional keybase bridge

* add keybase to bridgemap

* send to right channel, try to figure out received msgs

* add account and userid

* i am a Dam Fool

* Fix formatting for messages, handle /me

* update vendors, ran golint and goimports

* move handlers to handlers.go, clean up unused config options

* add sample config, fix inconsistent remote nick handling

* Update readme with keybase links

* Resolve fixmie errors

* Error -> Errorf

* fix linting errors in go.mod and go.sum

* explicitly join channels, ignore messages from non-specified channels

* check that team names match before bridging message

matterbridge.toml.sample

@@ -522,6 +522,29 @@ StripNick=false
 #OPTIONAL (default false)
 ShowTopicChange=false
 
+###################################################################
+#
+# Keybase
+# You should have a separate bridge account on Keybase
+# (it also needs to be logged in on the system you're running the bridge on)
+#
+###################################################################
+
+[keybase.myteam]
+
+# RemoteNickFormat defines how remote users appear on this bridge 
+# See [general] config section for default options
+RemoteNickFormat="{NICK} ({PROTOCOL}): "
+
+# extra label that can be used in the RemoteNickFormat
+# optional (default empty)
+Label=""
+
+# Your team on Keybase.
+# The bot user MUST be a member of this team
+# REQUIRED
+Team="myteam"
+
 ###################################################################
 #slack section
 ###################################################################