made memcached dependency optional

lib/kvstore/memcached.js

@@ -56,7 +56,6 @@ function del(key, cb) {
   );
 }
 
-
 module.exports = {
   connect: function (options, callback) {
     if (!client) {

package.json

@@ -17,7 +17,6 @@
     "node": "0.10.x"
   },
   "dependencies": {
-    "memcached": "0.2.2",
     "hapi": "1.1.0",
     "compute-cluster": "0.0.7",
     "jwcrypto": "0.4.3",
@@ -32,6 +31,7 @@
     "jshint": "0.9.1"
   },
   "optionalDependencies": {
+    "memcached": "0.2.2",
     "mysql": "0.9.5"
   }
 }