adding the ability to add admin and other users to mongodb through recip...

...e, readme updates, kitchen integration tests
adds
- user_management recipe, which will require auth on mongo config
- user resource
- user provider
- users attributes
- user_management integration tests
Are these attributes not included if you do not include user_managment in your runList, or does this clash with attributes/dbconfig.rb if you do not include the user_management recipe?