Update README, TODO
 Don't rely on implementation details of 'struct event'

- Use dynamic event allocation functions instead
- Remove deprecated header file
Pass event_base object into PubNub
so that libevent usage is thread-safe in the face of other libevent usage in the same process
Add API for setting root CA certificates for SSL connections
tests: Add SubscribeMultiSubUnsubLeaveFlow
tests: Save request's urls to vector
tests: Fix SubscribeMultiSubUnsubLeaveFlow test
tests: Update SubscribeMultiSubUnsubLeaveFlow test
Fix libevent-demo
Merge branch 'develop' of https://github.com/pubnub/c into develop