Redis DB

Implementation of the redis client (redis-py).

This implementation uses the redis: setup from settings.yml. A redis DB connect can be tested by:

>>> from searx import redisdb
>>> redisdb.initialize()
True
>>> db = redisdb.client()
>>> db.set("foo", "bar")
True
>>> db.get("foo")
b'bar'
>>>

searx.redisdb.OLD_REDIS_URL_DEFAULT_URL = 'unix:///usr/local/searxng-redis/run/redis.sock?db=0'

This was the default Redis URL in settings.yml.