Add Engine to support github issues

Using github API V3 to retrieve issue information.

When generating the onebox it will indicate the status of the issue.
who opened it and  if closed who closed it and when.

it will also show the lables / tags of the issue.
![image](https://cloud.githubusercontent.com/assets/8693091/4330974/35630b76-3fbb-11e4-952b-aedf84d223e8.png)