New icon: confluence

Thanks @taeram.
Clarify README about issues vs. pullreqs for new emoticons.
Fix README header hierarchy.
Confluence icon was removed.
New emoticons: yougotitdude, clarence. Comeback: confluence
New: branch, continue, failed, successful, unknown
Merge branch 'master' of https://github.com/henrik/hipchat-emoticons
Updated branch icon
Merge branch 'master' of github.com:blackline/hipchat-emoticons