marvin test: snapshots improvements

test_01_snapshot_on_linuxvm_Root_volume
test_02_snapshot_on_windowsvm_Root_volume

marvin integration test: snapshot improvments

1. test snapshot on linuxvm root volume
2. test snapshot on windows vm root volume

Signed-off-by: sanjeevneelarapu <sanjeev.neelarapu@citrix.com>
Incorporated the review comments.
1.Removed unused service dictionaries.
2.Removed trailing spaces
3.Removed test runner code (__main__)