Julia support

Adding initial [Julia](http://julialang.org/) support.  Julia and Travis has been a love story for quite some time, with Travis powering the majority of testing for both the official language implementation as well as a good chunk of the available packages.  This PR attempts to bring Julia support to Travis.  As I this is my first attempt at writing Ruby code, so I suspect that things may be off here and there and any and all feedback is very much appreciated.  The tests passed locally using Vagrant, but `spec` is certainly the part which I have the least understanding of, please, do kick the tires.
@BanzaiMan I like that idea. I've extracted deprecation notices to a central place (not used, yet). Maybe we could turn this into a more generic build script "notfication/message/info" thing, that holds methods like, e.g. `deprecate(msg)`, `notice(msg)`, `beta(msg)`.