Fixed WebcamFacade runtime error.

The issue is described in
https://groups.google.com/forum/#!topic/python-for-android/EZ3gddVIooU
and fixed in
https://code.google.com/r/olapaola-android-scripting/

It is also possibly related to issue #584:
http://code.google.com/p/android-scripting/issues/detail?id=584