Python3 support

[reverson]

When I install under python3 I get the following error:

>>> from dogpush import dogpush
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.7/site-packages/dogpush/dogpush.py", line 229
    print '# team: TEAMNAME'
                           ^
SyntaxError: Missing parentheses in call to 'print'. Did you mean print('# team: TEAMNAME')?
>>>