Many MANIFEST.MF: Replace org.junit4 with org.junit (4.8.2)

Eclipse 3 has junit plugins org.junit (3.8), org.junit (4.8) and org.junit4, and the latter was often picked to get version 4.x.
Eclipse 3 has no longer has org.junit4.

By changing the MANIFEST.MFs to use org.junit;bundle-version="4.8.2", the code works for both branches.

This which makes it a lot easier to compare the two branches, because many plugins only differ regarding the junit settings. Comparing master and 4.x.x now really limits the differences to E4 related things!

Fixes #326