Translate the version qualifier using maven-antrun-plugin since we want
manifest-first and currently cannot rely on Tycho for the JGit build.
Introduce property for Eclipse p2 repository to enable builds against
other Eclipse versions.
Change-Id: I62c4e77ae91fe17f56c5a5338d53828d4e225395
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>