Switching to semver due to API additions

I should have done this back when I added support for toggle's second
argument.

All static-API projects of mine (mostly polyfills) are versioned with a
date up until there are any API changes. You can treat any of my
non-semver projects as 1.0.YYYYMMDD[rev] (rev is blank unless there are
multiple revisions from one day)

classList.js

@@ -1,6 +1,6 @@
 /*
  * classList.js: Cross-browser full element.classList implementation.
- * 2015-03-12
+ * 1.1.20150312
  *
  * By Eli Grey, http://eligrey.com
  * License: Dedicated to the public domain.