Renaming gateway.pay and gateway.saveClient methods to match with MP api

0.5.0

Upgrading lib version and contributors info

Added methods addCard and deleteCard to MP gateway

0.4.0

Merge pull request #1 from andersonba/master

Refactoring gateway.pay method to accept strict sale JSON object

v0.3.0 Refactoring pay method to accept strict sale JSON

Old 'gatewa.pay' signature was removed.
The new one obligates user to save client before execute pay method

Save Client method added to gateway

v0.2.0 - Save Client method implemented in MP gateway

sanitizeClient method created to guarantee that client data is always in
the expected order

First version

The only implemented method is pay that charges a float value (referrer to an order code) in the credit card of a new client