Ise

PR from: [joshand](https://github.com/joshand)

* Implement ERS CSRF Check for Enhanced Security
* Add CRUD methods for SGT, SGACL and EgressMatrixCell
* Add unit tests in the same style as other unit tests, execute tests with & without CSRF on ISE 2.4 and ISE 2.7
* Update README with examples

PR from: [joshand](https://github.com/joshand)

* Implement ERS CSRF Check for Enhanced Security
* Add CRUD methods for SGT, SGACL and EgressMatrixCell
* Add unit tests in the same style as other unit tests, execute tests with & without CSRF on ISE 2.4 and ISE 2.7
* Update README with examples

Bugfix
Removed `sys.exit()` from the module.