Replace tets in TestAskWiki.py for builtin doctest.testmod.

http://docs.python.org/2/library/doctest.html

Example usage:

ismaelvc@toybox ~/D/t/AskWiki (tests)> python2 AskWiki.py -v
Trying:
    from AskWiki import AskWiki
Expecting nothing
ok
Trying:
    wiki = AskWiki('en')
Expecting nothing
ok
Trying:
    wiki_info = wiki.ask('wikipedia')
Expecting nothing
ok
Trying:
    wiki_info[1070:1260]
Expecting:
    u'Wikipedia (i/\u02ccw\u026ak\u0268\u02c8pi\u02d0di\u0259/ or i/\u02ccw\u026aki\u02c8pi\u02d0di\u0259/ WIK-i-PEE-dee-\u0259) is a collaboratively edited, multilingual, free Internet encyclopedia that is supported by the non-profit Wikimedia Foundation.'
ok
3 items had no tests:
    __main__
    __main__.AskWiki.__init__
    __main__.AskWiki.ask
1 items passed all tests:
   4 tests in __main__.AskWiki
4 tests in 4 items.
4 passed and 0 failed.
Test passed.
Replace for builtin doctest.
Merge pull request #2 from Ismael-VC/tests

Replace test in TestAskWiki.py for builtin doctest.testmod.