Move EWF core files to their own folder, grunt build changes Closes #149 #137

Big changes here. Moved all folders containing CORE Excelsior files to `excelsior/` EWF JS will be in `/js/core`

also note the change to the package build, it's now `grunt pkg` instead of `grunt package`, i was sick of mis-spelling it when trying to build out a zip file.

@nys-its/excelsior-core please review and either pull or give a :+1: to say you reviewed this pull req so we can get it into Master and have an official 0.1.2 build.