Setup Travis for BrainBrowser

This sets up Travis CI to automatically run the grunt tests
(jshint, qunit) for any new pull requests/builds. It does this
by setting up an "npm test" (the Travis default for node_js
language repositories) target which invokes grunt. It also
adds a Build Status image to the README.
Added quotation marks around version number

Added quotation marks around the version number of node_js.
Merge pull request #228 from driusan/SetupTravis

Setup Travis for BrainBrowser