Adding ability to configure cluster node type

Deprecating cluster_disk_nodes in favor of cluster_nodes and cluster_node_type
Updating README to reflect cluster node changes
Updating tests to handle cluster config changes
Merge pull request #69 from brwyatt/Add-Node-Cluster-Type

Add node cluster type
Refactor rabbitmq::server heavily and rename it to rabbitmq::config.
This makes all the parameters come from the main rabbitmq class as
well as refactoring the wipe database stuff to be slightly more
portable.
Add the parameters and variables needed for rabbitmq::config.
Delete this.
Make sure we @ all variables to remove warnings.
Rework the spec tests to be appropriate to rabbitmq::config.
Add a rabbitmq_erlang_cookie as a replacement for grepping the file.
This could be a security problem, so I'll need community feedback on
how OK this is.
Rename these to add .erb.
Fix all the current spec problems but moving the cluster depreciation
handling back to rabbitmq::config and iterating over the right thing.
Document the other parameters.
Merge pull request #74 from apenney/refactor-server

WIP: Refactor rabbitmq::server to rabbitmq::config.
Fix this, guess you don't have to escape these.
Merge pull request #76 from apenney/docs

Fix this, guess you don't have to escape these.
Fix alignment, remove more broken \_ references.
Merge pull request #77 from apenney/docs

Fix alignment, remove more broken \_ references.
Add some more framework to hang tests off.
Merge pull request #78 from apenney/rspec-system

Add some more framework to hang tests off.