brainyquote.py: get_quotes returns wrong quotes

[prajwal72]

brainyquote.py: get_quotes returns first x quotes by the author instead of the quotes belonging to the said category

[Rits1272]

Got the bug will solve it till tommorow.

[yugaljain1999]

There is some error in get_quote function too, as there we choose randomly quotes sometimes it returns
(author_name,author_name) instead of (quote,author_name)...

[parammittal16]

Fixed it! plz review the PR.