Fix invalid route case

[coni2k]

If there is an invalid link, (ex. /content/invalid), it fails to go to /404 page and starts loading home page recursively, which keeps logging this error and hangs the browser;

VM681:8WARNING: Tried to load angular more than once.
VM681:21 Uncaught Error: Highcharts error #16: www.highcharts.com/errors/16

[coni2k]

This was happening simply because in route.js - getContentTemplateUrl function, it was trying to get that invalid resource from the server;
return '/_system/views/content/' + key + '.html?v=0.49.0';

Since that html file is not there, IIS returns the home page (web.config - url rewrite rules - "AngularJS Routes") and then creates this infinite loop.

Since this is only happening in content pages, instead of this function, all content routes was defined in route.js (at least as a temp solution) and invalid content case now falls into 'otherwise' block;
.when('/_system/content/allInOne', { templateUrl: '/_system/views/content/allInOne.html..
.when('/_system/content/basics', { templateUrl: '/_system/views/content/basics.html..
.when('/_system/content/home', { templateUrl: '/_system/views/content/home.html..