Adding IAM:PassRole check
Extracting statement iteration code into its own function.
Merge branch 'feature/flag_iam_passrole_privilege' into develop
Changing S3 get_bucket to use validate=False.

According to the documentation,
http://boto.readthedocs.org/en/latest/ref/s3.html
validation is only required if you are not sure the bucket exists.
Also, validation requires object-level access.  Removing validation for
less expensive operation and so security monkey can run with fewer
privileges.