Port to Python 3

[anmol27katyani]

No description provided.

[rhl-bthr]

Thanks
Tested, doesn't work

Logs:

Traceback (most recent call last):
  File "/usr/share/sugar/activities/panorama/pano.py", line 84, in run
    self.camera = camera.Camera(self.camlist[0], self.size, "RGB")
IndexError: list index out of range

[quozl]

@octamois, please don't port Sugargame within an activity; first do Port to Python 3 in Sugargame, and then when a new version is available, port Panorama to it.

@Pro-Panda, do you have a camera? A camera is probably necessary for testing Panorama.

[rhl-bthr]

Stale; Needs more work.

@octamois if you plan to fix the same, please reopen the PR with the fixes