Guard against testing an empty collection in case Services are not available.

Conflicts:
	comtypes/test/test_collections.py
Rely on Services that should be present even when authorized applications are not.

Conflicts:
	comtypes/test/test_collections.py
Merge remote-tracking branch 'origin/master' into fix-test-ienumvariant
Merge pull request #21 from enthought/fix-test-ienumvariant

Fix IEnumVARIANT test