Add support for running IOU devices on cloud instances

This PR adds support for running IOU devices on cloud instances.  At this point, you should be able to:

(uh oh, before you attempt this, see NOTE below)
- Add an IOU image to gns3-gui, as type cloud.  It will upload to Cloud Files while it makes you wait.  On my home connection, the 100MB image took about an hour to upload (about 70kB/sec).  Put cloud in the name so you know which image is usable in the cloud setting.
- Create a cloud server by clicking the button.  Thanks to Massi's recent fix, when the instance is green in the cloud inspector, you can proceed.
- Drop the IOU cloud image on the canvas.  After a few seconds the red box should go away.
- Click start on the device.  Within a few more seconds you should be able to..
- Right-click and open up a console to the IOU device.  Pressing enter, you should see an IOU# prompt.

NOTE: Getting the iourc license file properly done is truly hellish.  You should go to the get the new user guide from the gns3 jungle and follow the section on IOU closely.  The guide puts you through the steps of setting up a remote server (not cloud) using a VirtualBox vm.  The IOU license generator script relies on VM having a hostid of 00000000 and a hostname of gns3-iouvm.  I have done the same with the cloud instance to make it as simple as possible for users.  At any rate, if the iourc file works in the remote server case, it will also work for the cloud instance.  If you don't want to go through the pain, I have an iourc file that will work.

Background: When you drop the IOU device on the canvas in both the remote and cloud server case, gns3gui takes care up uploading the iourc file to the server over the websocket connection.