Fix iOS testing

It looks like the primary issue with iOS tests failing was that some things require the actual simulator to be running before they work now, see https://github.com/facebook/xctool/issues/269 for more information. I created a minimal app that moved the tests from logic tests to application tests.

There were a few other issues with the tests themselves as well that I believe I have fixed:
* The HTTPBin certificates were old so I updated those. 
* Some of the pinning tests were broken because there was a change that forced verification of the entire certificate chain and the HTTPBin root and intermediate certificates were missing so I have added those and added them to the tests. 
* There was also an issue with the leaf checking when verification of the certificate chain is disabled.