Restrict mustache version. Fix laktek#25

which is related to janl/mustache.js#257. Thanks to @jbourassa for
digging this.

package.json

@@ -23,7 +23,7 @@
 											 , "less" : ">= 1.3.0"
                        , "marked" : ">= 0.2.5"
                        , "mime" : ">= 1.2.5"
-                       , "mustache" : ">= 0.5.2"
+                       , "mustache" : ">0.7.0 || >=0.5.2 <0.7.0"
 											 , "sftp" : "git://github.com/laktek/node-sftp.git"
                        , "uglify-js" : ">= 1.3.3"
                        , "underscore" : ">= 1.3.1"