Add Kelowna 2012 imagery source

Rational for setting default:

* Far superior colour and contrast
* Age within 6 months of bing
* Better alignment to GPX in hills
* Equal alignment to GPX downtown
* Probably more accurate anyways, being taken for the city's GIS department
* 10cm/px imagery, while bing is ~50cm/px

Shortfalls
* Not hosted on a server as powerful as Bing
Merge pull request #40 from pnorman/kelowna2012

Add Kelowna 2012 imagery source