[ACHIEVEMENT] Added member achievement (#40)

* added member achievement

* changed pullRequest.author to pullRequest.creator

* fixed image extension

* added pullrequest number to achievement title

* fixed time to wait :-)

achievements/member.achievement.js

@@ -0,0 +1,31 @@
+var moment = require('moment');
+
+var member = {
+  name: 'Member?',
+  check: function(pullRequest, shall) {
+    if (isWaitingLongTime(pullRequest)) {
+
+      var achieve = {
+        avatar : 'images/achievements/member.achievement.jpg',
+        name : 'Member pull request #' + pullRequest.number + '?',
+        short : 'Member Commits? member Push? member PR? ohh I member',
+        description : [
+          'A pull request you\'ve created 2 weeks ago',
+          ' is finally merged'
+        ].join(''),
+        relatedPullRequest: pullRequest.id
+      };
+
+      shall.grant(pullRequest.creator.username, achieve);
+    }
+  }
+};
+
+function isWaitingLongTime(pullRequest) {
+  var backThen = moment(pullRequest.createdOn);
+  var now = moment();
+
+  return now.diff(backThen, 'weeks') > 2;
+}
+
+module.exports = member;