Deployment target updates and tracing events

Release on 2018-11-30. All issues associated with this milestone can be found using this
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Added

• Migration Guide for SQift 4 and added it to the README.
  • Added by Jereme Claussen in Pull Request #16.

Updated

• Deployment targets to iOS 9.0, Mac OSX 10.11, WatchOS 2.0 and tvOS 9.0.
  • Updated by Jereme Claussen in Pull Request #16.

Removed

• Connection.trace in favor of Connection.traceEvent()
  • Removed by Jereme Claussen in Pull Request #16.