Fixes it so it can compile correctly for the latest version of Xcode / iOS SDK.

Code that directly creates a Bluejay.CharacteristicIdentifier from a CBCharacteristic needs to change to accommodate the fact that initializer is now fallible due to changes in the optionality of CBCharacteristic.service

Also includes a few smaller changes:

• Add setting to broadcast errors sent to cancelEverything to all listeners.
• Fix problem with timeouts in writeAndAssemble not working as expected if partial data is received
• Fix problem with the queue not restarting after transferring bluetooth state back to Bluejay