* Fixes #47 : Reorganize for 3.x releases, reduce duplication
Don't mention the current version in a section header. Badges should be
sufficient, and they don't need manual update.
Update repository links to the 3.x branch.
Consolidate "Current version" and "Project status updates" sections into
one "Project status" section. Avoid some duplication with "Contributions
welcome".
Update the twitter link, the logo image was broken. Use the "follow"
button instead.
Show "Still on Mockito 1.x?" in bold. Clarify the difference between 3.x
and 2.x releases.
Remove all forward looking statements about the next major release. They
are hard to update by anyone but the core developers, and don't provide
much value.