Add a build system, based on grunt. !!Requires changes to nginx configuration!!

Define package.json and Gruntfile, using jshint, concat and a custom mergeTemplates tasks.
Fix the issues reported by jshint.
Changed "app.tpl" into "app.xml" to avoid impact on mime.types
nginx config:
	- update worldcup2014 config file (serve all statics from nginx)
	- I recommend setting application/xml as mime type for xml (but text/xml works as well)