PycodestyleBear: Process whole output

[areebbeigh]

This commit modifies process_output to process all the detected problems instead of just the first one.

Fixes https://github.com/coala/coala-bears/issues/2882

Checklist

• [x] I read the commit guidelines and I've followed them.
• [x] I ran coala over my code locally. (All commits have to pass individually. It is not sufficient to have "fixup commits" on your PR, our bot will still report the issues for the previous commit.) You will likely receive a lot of bot comments and build failures if coala does not pass on every single commit!

[areebbeigh]

Can you add test cases to check and enforce PycodestyleBear processes whole output? That would be good ^^

Done.

[bkhanale]

~@areebbeigh Did the tests pass locally, I'm having some trouble running the tests.~

nvm

[areebbeigh]

needs a rebase

Done.