Added functionality to create a wmts tilegrid and wmts source from the
capabilities object created from ol.format.WMTSCapabilities.read().
Added tests for these functions and an example.
Also altered the REST url template replacement to be case insensitive
and added tests for this. This is because the spec uses both style
and Style and both of these are used by existing WMTS services.
Julien Enselme
Bart van den Eijnden
Sara Metz
Hadrien Tulipe