Feature/libraries

**Important commit: https://github.com/clearsightstudio/middleman-template/commit/70bdf727811cc1942ac48ae958d5b1e48a1a2b3b**


Added composer for managing libraries. Installed first library - phpmailer. 

Added an updated mailer script based on the phpmailer example script and the crappy mailer script that I created before. It's much simpler. The only magic field that can be added to the form markup is `<input name="ajax" />` which will return proper headers vs redirecting. Not sure if this needs to be documented. 

@jamonholmgren @ryanlntn @silasjmatson @carlinisaacson @kevinvangelder