vmwareapi: make method signatures match parent class

Fix any inconsistencies in method signatures between the
vmwareapi driver impl and the ComputeDriver parent class.
Add a test case to prevent future regressions

Closes-bug: #1333219
Change-Id: Ic361a922a1aefa5b5a3470c0547e694d073d2d58
Merge "vmwareapi: make method signatures match parent class"