Changes

Try to stabilize core tests

EGit tests have become unstable. A common culprit is
GitMoveDeleteHookTest, which seems to suffer from two things:

* File timestamp resolution running asynchronously.
* Index diff updates still running when the workspace is torn down.

So force synchronous file timestamp resolution determination, and wait
for index diff jobs before tearing down.

Change-Id: I1758aa2d28d00c13b730371198910ac7ae1a9d87
Signed-off-by: Thomas Wolf <twolf@apache.org>