Remaining flake8 fixes.
TastyPie supports 1.7, put back in Travis testing.
Update conf/makemessages to work called directly.

Requires Django 1.7, for next commit. Updates .po files, manually fixing
"View" variable name changes, and including new zh_TW translation.
Backport blocktrans' trimmed option.

This is so it makes nicer templates and translation files of large
strings, without having to demand Django 1.7 whilst older versions are
still supported.
Update requirement to pull in Spanish translation.
Bundle .mo files for availability after install.

Fixes #356.