Take two of management module

This attempts to just create one client connection ever. It is then up to the
caller to make sure they set all the proper attributes before the first
rabbitmq resource they call (besides the default or _config resources).

A future update would be to verify the options of the client connection are
consistent with what's in attributes, but this is an acceptable pass, and
eliminates much of the garbage from before. I've also verified that the right
values get updated if you set attributes.
Use new RabbitMQ::Management stuff (for the last time).

Uses the RabbitMQ::Management module, which is now a module yet again. Calls
new rabbitmq_client method to create or access the existent client connection
and uses rabbitmq_admin_user to grab the current value of the admin username.
Revert permissions for rabbitmq_binding after creation.

We have to elevate the admin user's access to the virtualhost upon which a
RabbitMQ binding is created, as read, write, and configure are all required to
declare a binding.

However, this is kind of a strange case to uniquely ruin the semi-secure model
of configure-only for, so we can set the permissions back to the way they were
after we declare the binding.
Slightly more idiomatic Ruby
Merge branch 'master' into take-2
Create a new RabbitMQ API client every action on every resource
I really hate Ruby/Chef sometimes.

Chef/Ruby does some weird coercion under the covers which means that by the
time node[:rabbitmq] gets to this library, the keys are strings instead of
symbols (even if you pass them in as such). This means there was both a for
example :admin_port and "admin_port" key to the hash, and they weren't getting
merged. We're gonna use 1.8 hash syntax because it works that way. PRs
accepted.

Please eliminate Chef from my life.
One more time ... constructor-based is fine

The problem the whole time was the string/symbol BS from last time. This format
is fine for getting the right values.
Fix reference to what should be admin_user
Fix admin_user
[1.5.0] Completely redo the API connection stuff (1 per resource) (#25)