Add usage info to readme
Added `USERPROFILE` environment variable for Windows

The `HOME` environment variable on Windows is call `USERPROFILE`.
Merge pull request #34 from alquerci/add/homepath_lookup

Added USERPROFILE environment variable for Windows for config path lookup
Added contributing informations

It's base on the [Symfony contributing standard][0].

[0]: http://symfony.com/doc/current/contributing/code/patches.html
Improve English in contributor guidelines
Merge pull request #48 from alquerci/add/contributing

Added contributing informations
Merge pull request #13 from nylen/add-usage-info

Add usage info to readme
Added a test for use a different mirror that the last update
Fixed the usage of a different mirror that the last update

Use only `<cachedir>/<arch>/setup.ini` to fetch all packages.
Added a note for back compatibility break for cyg-apt version 2