The acouchbase API should implement a custom EventLoopPolicy

Right now users need to get the event loop via our mechanism to obtain the event loop (from acouchbase import get_event_loop) prior to running any code. This works but is considered low-level and does not allow users to easily use asyncio.run() (specifically on Windows). We should validate our own policy so that we can either set our own policy or have users set the policy.

See the python docs on asyncio Policies.