Email layout and welcome

Responsive simple email template with Cachet styling. https://github.com/cachethq/Cachet/issues/100

More info: https://github.com/TedGoas/Cerberus

![screen shot 2015-01-01 at 2 10 20 am](https://cloud.githubusercontent.com/assets/1803556/5591872/a4a0cac2-915b-11e4-8761-405a1e89b0c9.png)