Dependency changes to enable install with latest EGit and Mylyn Reviews plugins

[selsemore]

• Loosen dependencies that prevent plugin from installing with latest EGit and Mylyn Reviews plugins.
• Eliminate usage of internal Mylyn class that no longer exists in latest Eclipse 4.2 downloads.

[buildhive]

Robert Munteanu » ereviewboard #8 FAILURE Looks like there's a problem with this pull request (what's this?)

[buildhive]

Robert Munteanu » ereviewboard #9 SUCCESS This pull request looks good (what's this?)