Rename Sites to Syndication Endpoints

[MattGeri]

• Applies patch from chetansatasiya:issue-10
• Fixes additional references to site and site groups
• Adds ui18n to labels
• Cleans up formatting on methods touched
• Adds unit tests for functionality touched

There was not much functionality that's worth testing in the methods touched. Any suggestions for additional tests is welcome.

[MattGeri]

Updated this to be version 2.1 compatible in #134.