* added google plus grant type

test still pending?
rename grant, remove from test
Default to UTF-8 for string payloads
Merge pull request #17 from soundcloud/feature/google-grant-type

Added Google plus grant type
consolidated and moved around constants
Merge remote-tracking branch 'origin' into feature/client-id-for-unauthorized-requests

Conflicts:
	src/main/java/com/soundcloud/api/CloudAPI.java