Fixed ResolveMerger regarding handling of deletions

Fixed ResolveMerger regarding handling of deletions

There was a bug in ResolveMerger which is one reason for
bug 328841. If a merge was failing because of conflicts
deletions where not handled correctly. Files which have
to be deleted (because there was a non-conflicting deletion
coming in from THEIRS) are not deleted. In the
non-conflicting case we also forgot to delete the file but
in this case we explicitly checkout in the end these files
get deleted during that checkout.

This is fixed by handling incoming deletions explicitly.

Bug: 328841
Change-Id: I7f4c94ab54138e1b2f3fcdf34fb803d68e209ad0
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>