Search Engine Optimization - API and Sitemap

Provided SEO related APIs:
- GetCollections: Retrieves the list of all collections grouped by supercollection.
- GetTimelines: Compelted support for Depth field

Provided sitemap.xml that is dynamically generated by calling the GetCollecitons API.

Code Review: http://mrccodereview.cloudapp.net/ui#review:id=1195
Deployment / Sample: cz-july2013-javierluraschi-fixes.azurewebsites.net/sitemap.xml