[SPARK-5335] Fix deletion of security groups within a VPC

Please see https://issues.apache.org/jira/browse/SPARK-5335.

The fix itself is in e58a8b01a8bedcbfbbc6d04b1c1489255865cf87 commit. Two earlier commits are fixes of another VPC related bug waiting to be merged. I should have created former bug fix in own branch then this fix would not have former fixes. :(

This code is released under the project's license.

Author: Vladimir Grigor <vladimir@kiosked.com>
Author: Vladimir Grigor <vladimir@voukka.com>

Closes #4122 from voukka/SPARK-5335_delete_sg_vpc and squashes the following commits:

090dca9 [Vladimir Grigor] fixes as per review: removed printing of group_id and added comment
730ec05 [Vladimir Grigor] fix for SPARK-5335: Destroying cluster in VPC with "--delete-groups" fails to remove security groups

Author: Vladimir Grigor

ec2/spark_ec2.py

@@ -1174,11 +1174,12 @@ def real_main():
                     time.sleep(30)  # Yes, it does have to be this long :-(
                     for group in groups:
                         try:
-                            conn.delete_security_group(group.name)
-                            print "Deleted security group " + group.name
+                            # It is needed to use group_id to make it work with VPC
+                            conn.delete_security_group(group_id=group.id)
+                            print "Deleted security group %s" % group.name
                         except boto.exception.EC2ResponseError:
                             success = False
-                            print "Failed to delete security group " + group.name
+                            print "Failed to delete security group %s" % group.name
 
                     # Unfortunately, group.revoke() returns True even if a rule was not
                     # deleted, so this needs to be rerun if something fails