Faster asyncpg queries via a global connection pool
Faster asyncpg queries via a global connection pool

In my benchmarks I was able to obtain a 17% performance
improvement over the current asyncpg demo code with a shared
connection pool.

Resolves: #540
See also: #531

ashleysommer/sanic,lixxu/sanic,lixxu/sanic,lixxu/sanic,r0fls/sanic,yunstanford/sanic,ashleysommer/sanic,ai0/sanic,r0fls/sanic,yunstanford/sanic,jrocketfingers/sanic,ai0/sanic,Tim-Erwin/sanic,yunstanford/sanic,channelcat/sanic,ashleysommer/sanic,channelcat/sanic,Tim-Erwin/sanic,channelcat/sanic,jrocketfingers/sanic,channelcat/sanic,lixxu/sanic,yunstanford/sanic