Merge pull request #79 from atlasapi/mbst-6948-sitemap-fixes

Ensure sitemap locations are not definitely for non-PC platforms.
Replace non-atomic remove/save with atomic update on single id, which should ensure that
a maximum of one record ever exists in the YV lastUpdated collection.
Merge branch 'mbst-7147-prevent-multiple-lastupdated-youview' into stage