Added support required for adapt_authoring

This includes:
- new 'grunt server-build' task, which allows building the framework in
  preparation for adding in the actual course JSON at a later time
- two new switch options:
  --theme - used to specify an Adapt theme
  --outputdir - used to specify a directory where the /build folder will
  be created, this is used in outputting to different folders, what would
  be different framework 'builds'
Changed package.json karma-mocha version

This was causing build failures in Travis.
Corrected issue with outputdir trailing slash

Corrected per the comments from @cajones.
Updated dependencies list

This is to allow 'grunt build' to run successfully when the 'production'
switch is used with npm install.
Bumped Node version number for Travis CI
Merge pull request #450 from adaptlearning/build-package

Changes required by adapt_authoring project