XMPPStream validatesResponses API

Facebook doesn't respond from the correct JID during negotiation so I making the validation of responses optional for now.
Upgrading GCDAsyncSocket to 7.4 branch, commit 5aa4d2145570ec0cd107e508ca0799b2df0dbabe
Fixing / upgrading Xcode projects
Adding support for SSL pinning. Fixes issue #333
Fixing sample projects to use new TLS certificate evaluation callback style.
Added element ID when requesting vCards
NSFetchedResultsController predicate updating
Merge pull request #366 from stephenwoodford/master

NSFetchedResultsController predicate updating
Merge pull request #362 from jonasman/master

Added element ID when requesting vCards
Fix Serverless Demo project
Merge pull request #370 from chrisballinger/serverless-demo-fix

Fix Serverless Demo project
fixed a compiler warning and make the interface compliant to the implementation
Merge pull request #374 from jonasman/master

fixed a compiler warning and make the interface compliant to the implementation
fix for merge fix
Merge branch 'master' of github.com:robbiehanson/XMPPFramework