set django_templates.fast = True

suggested by http://stackoverflow.com/a/9182798/240554
only concern is some warning of third party tags
and threadsafety that didn't sound like it applies to
us: https://docs.djangoproject.com/en/1.3/ref/templates/api/#loader-types
Merge branch 'master' into cached-loader
Merge pull request #139 from dimagi/cached-loader

set django_templates.fast = True