adding support for login using the Evernote app
Thrift ARC files
converting to ARC for all other files
adding documentation to all Evernote classes
fix problem with "_" in consumer keys.

Underscores are not allowed in callback schemes. More info here :
http://tools.ietf.org/html/rfc3986#section-3.1
bootsrapping by default, login with evernote app improvements and bug fixes

documentation updates
rename GCOAuth classes to avoid symbol collisions

moving ENConstants since it does not belong to internal
enabling ARC on the static library target

update README