Windows without a package aren't handled correctly

Clicking on a window that does not have a package results in this error:

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/contributor_console/utils.py", line 151, in do_call
    result = f(**kargs)
  File "/usr/lib/python2.7/dist-packages/contributor_console/utils.py", line 105, in identify_package
    pkg = out.split()[0][:-1]
IndexError: list index out of range

What should happen:

    An error message should be displayed saing that the the window does not belong to an application installed from a package.