Fetches, compiles and includes an external HTML fragment.
By default, the template URL is restricted to the same domain and protocol as the
application document. This is done by calling $sce.getTrustedResourceUrl on it. To load templates from other domains or protocols
you may either whitelist them or
wrap them as trusted values. Refer to Angular's Strict Contextual Escaping.
In addition, the browser's
[Same Origin Policy](https://code.google.com/p/browsersec/wiki/Part2#Same-origin_policy_for_XMLHttpRequest)
and [Cross-Origin Resource Sharing (CORS)](http://www.w3.org/TR/cors/)
policy may further restrict whether the template is successfully loaded.
For example, `ngInclude` won't work for cross-domain requests on all browsers and for `file://`
access on some browsers.