Actually ignore comment tags; and correct the expected output in the test case

examples/comments.txt

@@ -1 +1 @@
-<h1>A Comedy of Errors{{! just something interesting... or not... }}</h1>
+<h1>A Comedy of Errors</h1>

mustache.js

@@ -157,7 +157,7 @@ var Mustache = function() {
          lines[i] = lines[i].replace(regex, function(match, operator, name) {
            switch(operator) {
              case "!": // ignore comments
-               return match;
+               return "";
              case "=": // set new delimiters, rebuild the replace regexp
                that.set_delimiters(name);
                regex = new_regex();