Updated codemirror to v4.12.

Did a lot of cleanup to limit the size of the plugin.
I kept the emmet plugin.

applications/admin/static/codemirror/mode/css/scss_test.js

@@ -1,3 +1,6 @@
+// CodeMirror, copyright (c) by Marijn Haverbeke and others
+// Distributed under an MIT license: http://codemirror.net/LICENSE
+
 (function() {
   var mode = CodeMirror.getMode({indentUnit: 2}, "text/x-scss");
   function MT(name) { test.mode(name, mode, Array.prototype.slice.call(arguments, 1), "scss"); }