Make i18n tests quieter
pep8
Make all i18n scripts use argparse, handle --verbose flag
Added message to run during i18n tests to inform people that test_generate takes a long time
reraise exception without changing traceback
allow stderr if verbosity is off
tests only work when generate.main() is called with strict=False
pep8/pyflakes
create_dir_if_necessary() is unnecessary

We already have makedirs_p()
Merge pull request #2933 from edx/cale/quieter-i18n-tests

Make i18n tests quieter