Merge pull request AuthorizeNet#35 from sunnyrajrathod/master

- Updated contracts for xsd changes.

Merge pull request AuthorizeNet#30 from namanbansal/master

Adding code quality and package version widgets

Update setup.py

Merge pull request AuthorizeNet#26 from krgupta1/master

Providing set method to user to allow them to point to the sandbox or production env

Update setup.py

Merge pull request AuthorizeNet#15 from krgupta1/master

modifications to static function and writing error to stderr