Aioredlock

- Added the ability to get a lock object if the key and identifier was provided.

- Removed redis passwords from logs and error messages

Added
- Allow using Sentinels to handle redis connections
- Added a function on a lock manager to return check and return a list of all active locks

Changed
- Reverted back to using EVALSHA so that the scripts do not need to be uploaded for every command.
- Instead, if a script is not on the server for EVALSHA, then the exception is caught, the scripts are reuploaded, and the set is tried again.

Added
- Add watchdogs to extend lock's lifetime automatically

Changed
- Aioredlock totally becomes a lock manager, it track locks' state.When Aioredlock is destroyed, it releases all locks it have
- Remove ``lock_timeout`` and ``drift`` from Aioredlock's initialization parameter list and move them to ``Aioredlock.lock``
- Add ``internal_lock_timeout`` as default lock_timeout for Aioredlock initialization
- ``Aioredlock.lock(resource)`` is replaced by ``Aioredlock.lock(resource_name, lock_timeout)``
- ``Aioredlock.extend(lock)`` is replaced by ``Aioredlock.extend(lock, lock_timeout)``
- Remove lock_timeout from Redis' initialization parameter list

Added
- Support support for initializing aioredlock with an existing aioredis pool

Changed
- Move all closing logic from Redis.clear_connections() to Instance.close()
- Fixes for new version of asynctest