Remove duplicate template tags

@tdreyno - I noticed that there were duplicate tags in the template directory. Basically, the difference in string formatting like "coffeescript" versus "CoffeeScript" was making two links in the dl.sub-nav. So I went into the yml file and started by making the tag lists there consistent in style. I first went the route of naming things with capitalization where it seemed to make sense and this removed the duplication of tags now that all the tags had the same string value... but found that camel-casing was breaking stuff... like if all the templates with "CoffeeScript" as a tag would not show up on the templates/coffeescript route... so I made all the tags lowercase.

Didn't look elsewhere yet, but happy to dig around more and make improvements. Maybe this should be done at a programmatic level where the links are built so as to not rely on the tag strings needing to match exactly?