0.3.0 - Fixed Destinations

• Calls to external phone numbers (rather than just phone accounts) are now
  tracked correctly.
• The on_transfer hook was split to on_warm_transfer (for attended
  transfers) and on_cold_transfer (for blind and blonde transfers), with
  different method signatures.
• The on_b_dial events for a single call have been merged. If multiple
  destinations start to ring for a single call, one on_b_dial event will be
  triggered with a list of CallerId objects.
• The on_pickup event was removed. You can compare the data from the
  on_b_dial call with the on_up call to see whether the callee's phone rang.