Drush alias support

This PR add the ability to use drush aliases across sites. The purpose of this is to set up unique aliases that may change from team member to team member, thus making them not capable of being put into the repo. This makes sense for live sites too because now the aliases are created only for dev-ing purposes and if larger purposed are needed they can reside in other files. 

Does that make sense?

Also, since the thought is that this file is not going to get checked into the drupal project, the parsing of the json is the easiest approach to create an alias array with all the options.