Proj4js no longer needed for wmts-from-capabilities example

The WMTS capabilities document of the Vienna map has changed. It
no longer defines a tileset for EPSG:31256, so it can be parsed
without having Proj4js and a projection definition for
EPSG:31256.
Merge pull request #1280 from ahocevar/wmts-vienna

Proj4js no longer needed for wmts-from-capabilities example