added new backend: PagSeguro from Brazil
adding docs for PagSeguro
corrected docs indentation, added more docs. moved signal calls to get_gateway_url
added brazilian payment processor moip
adding docs for brazilian payment processor moip
removing pagseguro for now
fixing typos
adding xml encoding to moip backend
no longer using curl from command line. now using python's request lib.
Merge pull request #16 from bcarneiro/master

New payment processor: brazilian Moip