Patch Set 2:

- rebased onto current master
- I once hit the following exception when saving changed git preferences, maybe this is an interference with asynchronous refresh job run by repositories view :

java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793)
at java.util.HashMap$KeyIterator.next(HashMap.java:828)
at org.eclipse.egit.ui.internal.repository.RepositoriesView.unregisterRepositoryListener(RepositoriesView.java:435)
at org.eclipse.egit.ui.internal.repository.RepositoriesView.access$5(RepositoriesView.java:434)
at org.eclipse.egit.ui.internal.repository.RepositoriesView$6.run(RepositoriesView.java:359)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)