Add built locale files to .gitignore in release-1.7.x

We don't have any locale files in release-1.7.x, but the built .mo files may be
left over from when people were using master. Ignore them here, too.
Rename scmtools.crypto to scmtools.crypto_utils

On case-insensitive file systems, the import of 'Crypto' inside
scmtools.crypto will fail. This problem also appears when attempting to
run Review Board inside a Linux Virtual Machine, where the code has been
shared from a Mac OSX Host. Since the default OSX filesystem is
case-insensitive, case-preserving, the import will fail as well.

Reviewed at https://reviews.reviewboard.org/r/4483/