Add support for publishing and receiving generic properties on amqp messages so that things like arbitrary headers can be received.
Support addition of exchange creation options so that subscriber can auto-create the exchange if necessary/desired.
Merge branch 'exchange-options' into integration
Add declare_queue with options as a map.
Merge branch 'declare-queue-with-options' into integration
Add ability to convey additional state to Subscriber so implementers can stash other information in state.
Merge branch 'subscriber-user-state' into integration
Fix incorrect order in case statement.
Merge branch 'exchange-options' into integration
Add support for publishing and receiving headers on amqp messages.
Merge branch 'message-headers' into integration

Conflicts:
	lib/exrabbit.ex
read declare_exchange with map after weird merge.