using templating doesn't seem to work there; hardcode license URL instead

Tested the customizer, the generated zip had:
    css/bootstrap.css:line 6: * Licensed under MIT (<%= _.pluck(pkg.licenses, "url").join(", ") %>)
Revised customizer generates:
    css/bootstrap.css:line 4: * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)

docs-assets/js/customizer.js

@@ -8,7 +8,11 @@
 /* jshint multistr:true */
 
 window.onload = function () { // wait for load in a dumb way because B-0
-  var cw = '/*!\n * Bootstrap v3.1.0 (http://getbootstrap.com)\n\n *\n * Copyright 2013 Twitter, Inc\n * Licensed under MIT (<%= _.pluck(pkg.licenses, "url").join(", ") %>)\n */\n\n'
+  var cw = '/*!\n' +
+           ' * Bootstrap v3.1.0 (http://getbootstrap.com)\n' +
+           ' * Copyright 2013 Twitter, Inc.\n' +
+           ' * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)\n' +
+           ' */\n\n';
 
   function showError(msg, err) {
     $('<div id="bsCustomizerAlert" class="bs-customizer-alert">\