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
Do not allow bad keys while updating quota

Raise 400 (bad request) error instead of 200 (ok) if bad keys
are passed to the update quota request

Closes-Bug: #1248815

Change-Id: Iaefaa4961dd3783dfab15f843cbb2dcb12195a7d
Merge "Do not allow bad keys while updating quota"
Merge "Don't use deprecated module commands"