Updated BulkSMSGateway class to enable users to use other API servers by using the new setBaseApiUrl() method, this enable users that are using and have accounts on BulkSMS.co.uk (like in my case) to also use and benefit from this library.
Fixing up coding styles as requested as well as implementing the setBaseApiUrl() method into the other gatewway classes and added the setBaseApiUrl() to the interface too.
Corrected curly brace on new lines coding style issues (where I had accidently missed them from the last commit), also removed the type cast on setBaseApiUrl() methods.
Merge pull request #1 from bobsta63/master

Update gateways to allow different API endpoints to be used