Log Message:
Update net/ruby-amqp package to 0.7.4.

Here is partial changes:

= Version 0.7.2

  * [BUG] Server-named queues declared en masse now get their unique names \ 
instead of all beign assigned the first generated name
  * [API] Connection URI (string) format for vhosts no longer assumes that \ 
vhosts begin with a slash (/), learn more at http://bit.ly/mfzwcB
  * [BUG] Queue#reset leaks consumer tags [#40].