Fix circular dependend import

[onur]

Python3 is givin an error when we try to import gumbo1:

ImportError: No module named 'gumboc_tags'

This is because init.py is importing everything and gumboc_tags
already imported.

This patch is fixing this issue.

[nostrademons]

Travis is giving a test failure for this - it looks like it breaks Python 2?

Maybe try "from . import gumboc_tags" - I've seen this fix similar errors on other projects?

[onur]

It's just breaking tests because PYTHONPATH is not defined. from . import gumboc_tags might be a better solution for this.

[fake-name]

from . import gumboc_tags does not work:

>>> import gumbo
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.4/dist-packages/gumbo/__init__.py", line 33, in <module>
    from gumbo.gumboc import *
  File "/usr/local/lib/python3.4/dist-packages/gumbo/gumboc.py", line 29, in <module>
    from . import gumboc_tags
ImportError: cannot import name 'gumboc_tags'

---

Actually, the patch doesn't work either:

>>> import gumbo
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.4/dist-packages/gumbo/__init__.py", line 33, in <module>
    from gumbo.gumboc import *
  File "/usr/local/lib/python3.4/dist-packages/gumbo/gumboc.py", line 29, in <module>
    from gumboc import gumboc_tags
ImportError: No module named 'gumboc'

No idea why. I'm having library path issues, but I'm not sure how that interacts here.