[RFC/WIP] Add scrutinizer-ci.com config.

I just discovered Scrutinizer, a Coverity-like tool for Python (and PHP/Ruby) and ran it on Neovim's `python-client`. I enabled most of the possible code checks to see what it would come up with (that's why the `.scrutinizer.yml` file is so large; it's supposed to be [edited online](https://scrutinizer-ci.com/config-editor)). It will automatically run analysis on pushes and PRs or once per day, and it's free for open source projects. It integrates with Github, similar to Travis.

![untitled](https://cloud.githubusercontent.com/assets/339435/4495368/dff11cd2-4a5a-11e4-89c1-b9fc3cfb3313.png)

You can have a look at the analysis results [here](https://scrutinizer-ci.com/g/fwalch/python-client/?branch=scrutinizer). [![Scrutinizer Code Quality](https://scrutinizer-ci.com/g/fwalch/python-client/badges/quality-score.png?b=scrutinizer)](https://scrutinizer-ci.com/g/fwalch/python-client/?branch=scrutinizer)

I don't know how helpful this tool is, but I thought I'd share it with you. A minimal `.scrutinizer.yml` that only creates metrics and looks for duplicate code would look like this, by the way:

```
checks:
    python:
        code_rating: true
        duplicate_code: true
filter:
    excluded_paths:
        - test/*
```