boto's rds2 renamed `vpc_security_groups` to `vpc_security_group_ids`
and changed from a list of `VPCSecurityGroupMembership` to just a
list of ids. This accommodates that change when rds2 is being used.
- removed import of sys module.
- HAS_BOTO constant to check if import was successful.
- trigger a failure when import fails.
- removed unnecessary imports.
Using rds2 allows tags and the control over whether or not DBs are
publicly accessible.
Move RDS towards a pair of interfaces implementing the details of rds
and rds2
Added tests to ensure that all operations work correctly as well as
requirements files that allow virtualenvs to test either boto.rds or
boto.rds2
