Installation and configuration handled by rakefile

Fixes https://github.com/jamesandrewsmith/devtools/issues/20

Gives ability to configure each individual software passed in to be installed via the rakefile
Merge pull request #21 from jamesandrewsmith/feature/windows-packages-configure

Feature/windows packages configure
Restructured for osx support

* Configuration files broken down into global, and environment specific; windows, osx, etc.
Configuring git for windows

https://github.com/jamesandrewsmith/devtools/issues/22
Merge pull request #24 from jamesandrewsmith/feature/configure-git

Feature/configure git