Added missing files to setup.py

If I install Printrun via setup.py, I don't have gcoder.py and I cannot even
use pronterface.py:

Traceback (most recent call last):
  File "/bin/pronterface.py", line 46, in <module>
    import pronsole
  File "/usr/bin/pronsole.py", line 23, in <module>
    from gcoder import GCode

So I've added this to setup.py.

Also, pronsole.ico is missing, added that to (not needed at runtime, but is
usefull for desktop files)
Making the whole package GNU GPLv3+.
Merge pull request #300 from hroncok/master

Added missing files to setup.py and fixed license notice in files which were not explicitly gplv3+.