Updating Construction and WSDL Cache path determination / creation

- Moved much of the logic used in the constructor to static functions as I was seeing very weird intermittent behavior on older versions of PHP 5.3
- Fixed issue that would prevent a custom wsdl cache path being used on the first attempt
- Added ability to access certain properties in a read-only fashion via magic __get method
- Added a few additional PHPUnit tests.
Updating README.md