Provide ability to disable SSL certificates check.

There are sometimes cases in business appliance where one really wants to disable SSL checks, for instance during integration with third party systems it is not always possible to force them to update certificates used for https. 

Unit test is provided under integration tests section using washington university host. I would suggest providing proper endpoint at jsoup.org for that and refactoring unit test. 

11.11
- refactored code to do checks before aggressifve cast to HTTPSUrlConnection
- added proper unit test

This needs synchronization across multi threads. Maybe synchronize within the null check.

Also check code formatting style here.