* Adds custom_data parameter to azure virtual machine resource
Invoke custom_data in an integration test: This invocation of
custom_data should not cause any side effects.
* Bugfix: String encoding now works in both python2 and 3
* Fix pep8 violations
* Use nginx to serve a text file created via custom_data and verify that
that custom_data is working
* fix up azure_rm_virtualmachine custom_data
* tweaks #25924
* simplify string encoding fun
* don't rely on external packages