Don't use deprecated module commands

The commands module was deprecated since version 2.6 and it has been
removed in Python 3. Use the subprocess module instead.
See http://docs.python.org/2/library/commands#module-commands

Closes-Bug: #1248216
Change-Id: I4091179c6b312ae8534b30adc518eff67d68320a
Merge "Don't use deprecated module commands"