Change shebang lines to work universally

Using env enables the scripts to run in virtualenv as well as in a
differently named or bare environment.

Signed-off-by: Felix Kaechele <felix@kaechele.ca>

create_db.py

@@ -1,4 +1,4 @@
-#!flask/bin/python
+#!/usr/bin/env python
 
 from migrate.versioning import api
 from config import SQLALCHEMY_DATABASE_URI

db_downgrade.py

@@ -1,4 +1,4 @@
-#!flask/bin/python
+#!/usr/bin/env python
 from migrate.versioning import api
 from config import SQLALCHEMY_DATABASE_URI
 from config import SQLALCHEMY_MIGRATE_REPO

db_migrate.py

@@ -1,4 +1,4 @@
-#!flask/bin/python
+#!/usr/bin/env python
 import imp
 from migrate.versioning import api
 from app import db

db_upgrade.py

@@ -1,4 +1,4 @@
-#!flask/bin/python
+#!/usr/bin/env python
 from migrate.versioning import api
 from config import SQLALCHEMY_DATABASE_URI
 from config import SQLALCHEMY_MIGRATE_REPO

run.py

@@ -1,4 +1,4 @@
-#!flask/bin/python
+#!/usr/bin/env python
 from app import app
 from config import PORT