AsyncHTTPProvider extra dependencies

[ediskandarov]

What was wrong?

Installation of web.py python package by default required aiohttp in dependencies.

Async HTTP provider is not required until you specifically write async code(which is not a general case).

Thus it would be rational to move this dependency to extras.

How was it fixed?

Moved aiohttp to extra requirements.

Todo:

• Add entry to the release notes

Cute Animal Picture

[ediskandarov]

@kclowes @fselmo please review

[ediskandarov]

if there any way to push this forward?

[kclowes]

This seems like a reasonable change to me @emcpow2, especially since async is not in a complete state yet. I'll do some manual testing and merge soon! Thanks!

[kclowes]

For some reason the full test suite wasn't running on the PR, so it looks like we have a few failures that need to be addressed. However, after playing with this a little bit, I'm inclined to close this PR because my gut is telling me that async will be the primary way that people use web3 in the future. @emcpow2 do you have a particular reason/use case to remove the dependency, other than keeping the dependencies slim?

[ediskandarov]

Hey @kclowes . Yes, it's solely to keep dependencies as slim as possible.

Many projects will not welcome aiohttp in dependencies. (I have no attitude to the aiohttp itself, it just seems an overkill to explicitly require it)