[STF] corrected test cases

ShareProjectUsing... cannot work because the feature is currently
disabled because it is not working as expected.

ParallelInvitation... the test already states that it is not consistent.
Changed the logic that is performed here but currently there are other
issues so the test case currently lacks of assert statements.

Change-Id: If3c7cb999353b6b37331f849725ff129745f0f86
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1199
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>