Clear buffer before rendering. Closes #26.

mustache.js

@@ -17,6 +17,9 @@ var Mustache = function() {
     },
 
     render: function(template, context, partials, in_recursion) {
+      // reset buffer
+      // TODO: make this non-lazy
+      this.buffer = [];
       // fail fast
       if(!this.includes("", template)) {
         if(in_recursion) {