Tweak .less.css removal to be shell-generic
Use dennis_shim.py for 10x speedup

Turns out running dennis in ./manage.py is uber-slow because of all the
django/whatever stuff. Running dennis directly with a shim that sets up
the sys.path correctly is *so much faster*.

Also, this updates dennis to v0.3.8 which picks up a fix for false
positives in mismatched variables error detection.
Use compile-linted-mo.sh in deploy