Update README.md

Updated first example to use new subclasses Popularity and Page
Merge pull request #57 from AndrewBell/master

Update README.md
Merge pull request #55 from RaulLepsa/master

Comment-related functionality refactor
Removed occurrences of @author in the method's javadoc.
Updated README to point to the right location of implemented_methods.md"
Merge pull request #58 from sfat/master

Small improvements
Renamed com.github.jreddit.message.Comment to MessageComment in order to avoid confusion with the com.gihbub.jreddit.comment.Comment. The first is a comment(like a reply) from a message, while the latter is an actual Comment
Moved CommentsSort to Comments package and added missing CommentSort options
Added InvalidURIException to deal with Invalid location requests. Added it to the GET method
Renamed TypePrefix to Kind (more accurate naming for the reddit "kind" of a post), and added 2 more Kinds: LISTING and MORE