* Refactor common network shared and platform specific code into package (part-1)
As per proposal #76 refactor common network shared and platform specific
code into sub-package.
https://github.com/ansible/proposals/issues/76
* ansible.module_utils.network.common - command shared functions
* ansible.module_utils.network.{{ platform }} - where platform is platform specific shared functions
* Fix review comments
* Fix review comments
* netscaler_service initial implementation
* Changes as requested by reviewers
* Skip some tests if under python2.6 and importing requests library
* Change option "operation" to "state"
* Remove print statements from netscaler module utils
* Catch all exceptions during login
* Fix fail message
* Add common option save_config