Cleans up config files.

There were a few stray relics from dogestream that needed to be cleaned up
and/or ammended.

In particular, a new .travis.yml should be created for this project and a
proper mongo install configured. I can't remember what the issue was last
time but Travis was throwing a fit with how were using Mongo.

Also removed the Gemfile, since Nile no longer encompasses the front-end
implementation.

Finally, added dev-dependencies for Gulp, since it's cool and stuff and can
replace Make for our use case.