Authorise and destroy

This release adds support for:

• Providing arbitrary parameters to the underlying cljs-http request used with the HTTP transport. This allows, among other things, authorisation. See #13 for details, thanks to @chrisbetz
• Ability to destroy the re-graph state, including stopping all subscriptions and closing the websocket first. See #12 for details.

This release improves:

• Subscriptions are deduplicated by id, helping to reduce workload on servers which do not support deduplication #16
• Unsuccessful reconnection attempts no longer add messages to the websocket queue #17
• Should work better with advanced compilation #15