Drop dependency on ansible (six.moves)

As it is, aur.py depends on ansible being installed on the target host.
So, you would need to get ansible installed in your target host just to be able
to make use of aur.py and install whatever packages you need.

Let's review the dependency:

      from ansible.module_utils import six
      from six.moves import urllib

I reckon that the six¹ package is there to isolate an ansible module's code from
the particular major version of python being used (2 or 3).

Fortunately, since last week², the ansible package in archlinux now depends
directly on python3, so I reckon that in this particular instance, we can safely
import urllib.request directly, which from now on will be spot on.

To recap, current arch ships python3, and the arch ansible package depends on it
to run.  aur.py's purpose is to run on archlinux hosts, thus, python3 can be
safely assumed to be available.  So we can depend directly on it and relax the
dependency on ansible itself.

On a personal note, I am using this nice module to help me bootstrap my arch
systems, so not having to install ansible just to be able to use it makes my day
a little better :-)

Thanks a bunch!

[Feel free to edit the commit log]

[1]: https://pythonhosted.org/six/
[2]: https://git.archlinux.org/svntogit/community.git/commit/trunk?h=packages/ansible&id=bb1a1cc822891387d5a8b3dad0d0ccdee94c0c51

aur.py

@@ -2,8 +2,7 @@
 
 from ansible.module_utils.basic import *
 import json
-from ansible.module_utils import six
-from six.moves import urllib
+import urllib.request
 import tarfile
 import os
 import os.path