Fast caches for python.

Features:

• Sync and async caches (cachel.base.BaseCache and cachel.base.AsyncBaseCache).
• Cache decorator supports sync and async (for python >= 3.5) functions.
• Batched requests via .objects decorator method.
• Explicit cache keys.
• Custom ttl for returned values (cachel.expire).
• Configurable serializers: (none, unicode, json/ujson, msgpack, pickle).