Support for behaviors of pylibmc

[cic79]

I am using django-environ and pylibmc as backend.
It would be nice to be able to set behaviors directly in the env.
Something like:
CACHE_URL=pymemcache://127.0.0.1:11211?TIMEOUT=6000&BEHAVIOR:ketama=1&BEHAVIOR:remove_failed=1&BEHAVIOR:retry_timeout=1&BEHAVIOR:dead_timeout=60

CACHES = {
    'default': {
        'BACKEND': 'django.core.cache.backends.memcached.PyLibMCCache',
        'LOCATION': '127.0.0.1:11211',
        'TIMEOUT': 6000,
        'OPTIONS': {
            'behaviors': {
                'ketama': 1,
                'remove_failed': 1,
                'retry_timeout': 1,
                'dead_timeout': 60
            }
        }
    }
}