HAPI v17+ support!

##Breaking changes

Constructor no longer accepts a callback for initialization. Instead, use await server.init() to manually call this. server.start() will call init if not already done so.
server.start and server.stop are now async functions, which no longer accept callbacks
config.hapiConnectionOptions and config.port has been removed. use config.hapiServerOptions instead.
Theoptions.extensions modules support async functions and promises. Callback methods are deprecated but may still work internally via util.promisify.
If you use older plugins and routes with hapi, you'll have to update your route handlers and plugins to support hapi 17+

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