Manage bindings between exchanges

[jdlourenco]

Hi there,

I added methods for creating, deleting and getting info about bindings between exchanges.

I've been using RabbitMQ and your gem for quite some time now and never needed this feature but since I needed to add this to my application I thought it would be nice to add it to your gem.

I've also added rspec tests that run successfully on my setup and bumped gem version in order for you to publish it if you decide to merge my code.

Best regards, Jose

[michaelklishin]

Thank you.