Provide for and introduce the use of pillars in our salt config

Pillars will allow us to specify various data sets depending on the server that we're configuring. Right now we only have one–the virtual environment–so we don't have to get too fancy. The first pillars data includes a few plugins that we want to loop through to install.
Loop through plugins pillar and install each listed plugin
Use $is_args in nginx config to either use ? or "" depending on need for args
Merge pull request #1 from washingtonstateuniversity/install-multiple-plugins

Use pillars to aid in the install of multiple plugins