Added tests for Nova microversion v2.47

This microversion changes flavor property in server response.
New test case was added to do not overload some other testcase
by running all tests for two microversions (v2.1 and v2.47)

Also method create_test_server was modified. Now it adds field
'network' into request if microversion >= v2.37 because since
this microversion this field is required.

Change-Id: If7420d0c6153fe63c049c0f6dc9a748968d40315
6 files changed