* update integration tests for updated boto exception message
* integration tests fail on both "test credential" test cases
exception bubbles out of module. instead catch and wrap
* ec2_group does not support updating a security group's description
AWS security group descriptions are immutable.
if ec2_group finds a group that matches by name, but the descriptions do not match, the module does not support this case
previously it would check if the group was used, but would not do anything if it was
old behavior was erroneous because it could make a user expect that the description change of a group was fine when in fact it did not occur
also, it made an expensive check against all ec2 instances for no good reason
* comments not doc strings
* else must have pass w/o doc-string statement
* Catch specific BotoServerException, give context around error when fetching SGs
* python3 compatible exception blocks
* add traceback to fail_json
* two blank lines before first function
* description is only required when group state is present
also note that AWS requires a non-empty description when creating a security group
* clarify description requirement
