Show correct filename case in template loading error
Kostache_Layout: Load content as mustache source

This fixes issues caused by the content partial being rendered and then
injected as a partial in the layout template and being rendered again
Merge pull request #61 from EvanPurkhiser/fixup/issue-55-layout-renderer

Kostache_Layout: Load content as mustache source
Merge branch 'develop'
Merge branch 'master' of https://github.com/paulsschwarz/KOstache