Optional arguments for exchanges are not exposed in the API

[michaelklishin]

See #191 for the background.

As with other options, they can still be defined using a policy.

[michaelklishin]

Apparently they are, somehow GitHub search failed me :(

From ExchangeIntegrationTest.swift:

let conn = RMQConnection()
conn.start()
let ch = conn.createChannel()
let x = ch.fanout("objc.tests.fanout", options: [], arguments: [])

From RMQMethods.h:

@interface RMQExchangeDeclare : RMQValue <RMQMethod>
@property (nonnull, copy, nonatomic, readonly) RMQShort *reserved1;
@property (nonnull, copy, nonatomic, readonly) RMQShortstr *exchange;
@property (nonnull, copy, nonatomic, readonly) RMQShortstr *type;
@property (nonatomic, readonly) RMQExchangeDeclareOptions options;
@property (nonnull, copy, nonatomic, readonly) RMQTable *arguments;
- (nonnull instancetype)initWithReserved1:(nonnull RMQShort *)reserved1
                                 exchange:(nonnull RMQShortstr *)exchange
                                     type:(nonnull RMQShortstr *)type
                                  options:(RMQExchangeDeclareOptions)options
                                arguments:(nonnull RMQTable *)arguments;
@end