Added several new endpoints for accessing iam groups and users,
include unit tests.
Added get_user and delete_access_key endpoints.
Added support to get_all_security_groups endpoint to actually filter groups.

 - Filters by groupnames, group_ids and a filters. However, the filters option doesn't
   support owner-id and tags since neither attribute was readily available via the SecurityGroup object.

 - Also included a basic test to confirm it works.
Fixed py26 errors related to using assert_raises in tests.
Fixed py33 errors.
Fixed stupid "random_alphanumeric" typo that got repeated due to tab completion.
Merge pull request #184 from invenia/master

Additional IAM endpoints