Rebuild Terra CLI using RoboPHP as a Framework.

I only discovered RoboPHP about 6 months ago, but as soon as I saw it I knew it was something we needed.

This PR changes Terra CLI to use RoboPHP "as a framework": See http://robo.li/framework/

This code is only at the beginning stages. The only working command is app:add.

The mission of terraCLI is not just to launch some docker containers, but to handle all of the things you typically need to do when building "websites" with as few commands as possible.

Things terra does now that RoboPHP can do for us now (in this PR):

Exec
Git clone: http://robo.li/tasks/Vcs/ (Note robo has support for Hg and SVN)
Composer Install
Behat Tests: http://robo.li/tasks/Testing/#behat
Docker-compose.

Things RoboPHP does that we would love to use, but don't yet:

Assets watching and processing
SSH & Rsync for potential remote environment management.
More Testing: http://robo.li/tasks/Testing/
Bower & Gulp
Advanced Docker (building images locally, firing up extra images like Solr or Redis)
... ?

terra-ops / terra-cli

Rebuild Terra CLI using RoboPHP as a Framework. #130