Creating the dev role

This role include the base role, but adds the following:

* zsh
* build-essentials (autoconf, etc.)
* rubies for 1.9.3-p484, 2.0.0-p353 and 2.1.0 (default)
* redis
* memcached

Both redis and memcached are daemonized, set to run on start up and use their respective default ports.