delete python bytecode before every test run

Bring over the cleaning line from run_tests.sh for the pyc files to
all the tox runs.

This should eliminate the need to clean -x -i to kill pyc files in
your local directory to get tests to pass.

Closes-Bug: #1368661

Change-Id: Idf3a46d8c95806f2d2ce28ce84ced12b625e53df
correct inverted subtraction in quota check

From a user reported bug: we were doing the subtraction backwards
here, causing int overflow, causing all kinds of invalid. Instead
actually subtract the smaller number from the bigger number.

Change-Id: I7c099df5e31aa25b8be65c570e2e0b8a3e93c277
Closes-Bug: #1363324
Merge "correct inverted subtraction in quota check"
Merge "delete python bytecode before every test run"