Run JSHint and build on Travis CI for dev 0.3

Yet another attempt to build on Travis CI.

This PR adds several nice features:
 * JSHint is being run on Travis to verify that committed code (and pull requests) don't contain any syntax errors and follow basic guidelines of Javascript code
 * Builds are split into 4 parts - one for each platform and jshint - so we can quickly identify where the error has occurred

Currently the build is broken, so I can't 

Last commit here also fixes several syntax errors for latest code. See sample output at https://travis-ci.org/vrutkovs/popcorn-app/builds/21827267