asyncio support

[madeinoz67]

Thanks for this package, just starting to use in my OS project and would like to see async supported.

I know ultimately its accessing a file locally, however this has been done in a similar fashion with sqlite using the aiosqlite driver.

[jorants]

Would be nice, even just a 'fake' asyncio interface so that montydb can be used instead of motor in testing.

[davidlatwe]

Thanks, this would be the next goal once #26, #27, #38 are resolved. :)

References:

• https://github.com/omnilib/aiosqlite
• https://github.com/mongodb/motor