Allow for pre-defined environments

[stuartshields]

@bradp So you have support for pre-selected extensions to be installed, what I'm wondering is, could you have a list of predefined extensions for different environments? i.e: WordPress.com VIP would pre-select the VIP Classic extension, XDebug etc.

[bradp]

Good idea! I did something similar with blueprints in vv, would make sense to have this for sure.

[stuartshields]

@bradp The other alternative I had was to fork this repo and create the VIP pre-selected extensions. However that would be overkill.

IF we do go the path of creating this, be aware that we'll need to add https://github.com/stuartshields/vip-debugging to the list since currently the debugging extension causes issues because of mu-plugins in the VIP extension already having the rewrite rules extension.