fix automatically_recover config option

[AlexNimoy]

If option automatically_recover: false and automatic_recovery not set

opts[:automatically_recover] || opts[:automatic_recovery] #=> nil Other cases

false || nil #=> nil
nil || false #=> false

false | nil #=> false
nil | false #=> false

automatically_recover? return nil https://github.com/ruby-amqp/bunny/blob/master/lib/bunny/session.rb#L456

# @return [Boolean] true if this connection has automatic recovery from network failure enabled
def automatically_recover?
  @automatically_recover
end

[michaelklishin]

Thank you!