Added ability to add multiple users to databases on same instance
Added test for rackspace  databases multi user create
Some code cleanup
[doc] Added documentation for the createUser method for the rackspace databases api
Added regex and length restrictions for username/password/database when creating users for a rackspace database
[fix] Fixed race condition that I had previously implemented
Added test for adding user with invalid characters
[test] Fixes offline test failures mentioned in #81
Merge pull request #82 from jcrugzz/rackspace-databases-users

[api][rackspace]Added ability to add multiple users to databases on same instance