Tag soup 1.2.1

Unfortunately, there's no option for creating a new branch when sending a pull requests.

This PR updates TagSoup to 1.2.1, which fixes at least 2 issues with doctype case-sensitivity. 

I can confirm that my application still works after that upgrade just fine, no noticeable changes.

Also, please note that i've added Leiningen version check (min of 2.0.) because of used :profiles section that's used for :resource-paths for tests.