allow delimeter specification

Author: itsdiay

lib/index.js

@@ -21,6 +21,7 @@ module.exports = (options = {}) => {
       let subtree;
       let source;
       let locals = false;
+      let delimiters =  options.delimiters || ['{{','}}'];
 
       if (src) {
         src = path.resolve(options.root, src);
@@ -33,7 +34,7 @@ module.exports = (options = {}) => {
 
         if (locals) {
           const result = posthtml()
-            .use(expressions({locals}))
+            .use(expressions({locals, delimiters}))
             .process(source, {sync: true});
           source = result.html;
         }