Prepare 4.2.0 release

[torchhound]

[4.2.0] - 2019-10-25

Added

• The identify function allows a completion to be called after a user is updated.
• The Connection Status API allows greater introspection into the current LaunchDarkly connection and the health of local flags.
  • This feature adds a new class called ConnectionInformation that contains properties that keep track of the current connection mode e.g. streaming or polling, when and how a connection failed, and the last time flags were updated. This class can be accessed from LDClient.shared.getConnectionInformation.
  • Additionally, a new observer function called observeCurrentConnectionMode allows your application to listen to changes in the SDK's connection to LaunchDarkly.

Changed

• The user property is now deprecated in favor of the identify function.