Asynchronous refactoring using RQ.

* when a new event arises, it's sent to a background worker and the PR
  state is set to pending.
Deployment section in the README

* How to setup the worker in a production environment
Merge pull request #7 from greut/async

Asynchronous refactoring using RQ
PEP8 checks on the whole files.
PEP8 errors into the review view.

* The commit messages error displayed into the commit itself and the file
  related comments are put into the review view (on line 1)
Merge pull request #8 from greut/pep8

PEP8 checks on the whole files
Fix multiline bullet point seen as signatures.
PyFlakes checks on the whole files.
Refactoring.
Options in config for commits, pep8, flakes, wip.
Merge pull request #9 from greut/fix-multiline-bullets

Fix multiline bullet point seen as signatures.
Merge pull request #10 from greut/pyflakes

Pyflakes support