MOBSDK-558/573/578

MOBSDK-558: a test has been added to the VersionServiceTest class to check on the versionLabel, once a document node is updated on a Cloud server.
MOBSDK-573/578: creation of test files and folders on the server now are created based on their filename plus timestamp. This is to avoid collisions.

All unit tests are pending Cloud verification at the moment, so I am not going to close the JIRA tickets just yet.

Also: the tests referred to properties and methods using super, which is not needed. This has been replaced with self as should be.