Added Instagram's implementation

Tested getContactList with a custom application and worked. There might
be dependencies with other classes.
added feed plugin and custom permissions support

and fixed some typos
improved some methods

reduced dependencies from global variables in InstagramImpl. Included a
message field in feeds returned by feed plugin
Merge branch 'master' of https://github.com/kpsychas/socialauth into kpsychas-master

Conflicts:
	socialauth/src/main/java/org/brickred/socialauth/SocialAuthConfig.java
Resolved bugs