Updating mnesiadir attribute and copying erlang cookie to /root

so that things work again on SmartOS.
Reading the erlang cookie file only if it's there
More tweaks to get user and plugin management working (again) on SmartOS

Signed-off-by: Adam Kalnas <a.kalnas@modcloth.com>
Tweaks to clustering setup, plus still fighting with epmd
Fixing a goof in the rabbitmq.config template

and de-duping definition of the /root/.erlang.cookie template.
Making some repeated resources unique so that they don't overlap
Removing a bunch of defaults so that DeepMerge from data bags works as expected
Making cluster disk node configuration true to its name
Merge pull request #1 from modcloth-cookbooks/smartos

Getting things working on SmartOS again