Merge pull request #154 from steemit/v0.5.11

Update version to 0.5.11

package.json

 {
   "name": "steem",
-  "version": "0.5.9",
+  "version": "0.5.11",
   "description": "Steem.js the JavaScript API for Steem blockchain",
   "main": "index.js",
   "scripts": {