[test_ec2*] cloud integration test updates

To support parallel cloud test execution, create and provide a random string to
cloud integration tests.  The variable 'resource_prefix' can be used in cloud
roles and during resource cleanup to safely create/destroy cloud-based
resources.

Additional changes include:

 * The roles test_ec2_key and test_ec2_group were updated to use to
 {{resource_prefix}}.

 * Additionally, the Makefile was updated to set resource_prefix to a random
 string.  The Makefile will also use 'resource_prefix' during cloud_cleanup.

 * All test_ec2* roles were updated to add 'setup_ec2' as a role dependency.

test/integration/cleanup_ec2.py

@@ -15,7 +15,7 @@ def delete_aws_resources(get_func, attr, opts):
     for item in get_func():
         val = getattr(item, attr)
         if re.search(opts.match_re, val):
-            prompt_and_delete(item, "Delete object with %s=%s? [y/n]: " % (attr, val), opts.assumeyes)
+            prompt_and_delete(item, "Delete matching %s? [y/n]: " % (item,), opts.assumeyes)
 
 def prompt_and_delete(item, prompt, assumeyes):
     if not assumeyes:
@@ -23,6 +23,7 @@ def prompt_and_delete(item, prompt, assumeyes):
     assert hasattr(item, 'delete'), "Class <%s> has no delete attribute" % item.__class__
     if assumeyes:
         item.delete()
+        print ("Deleted %s" % item)
 
 def parse_args():
     # Load details from credentials.yml
@@ -74,8 +75,11 @@ if __name__ == '__main__':
     aws = boto.connect_ec2(aws_access_key_id=opts.ec2_access_key,
             aws_secret_access_key=opts.ec2_secret_key)
 
-    # Delete matching keys
-    delete_aws_resources(aws.get_all_key_pairs, 'name', opts)
+    try:
+        # Delete matching keys
+        delete_aws_resources(aws.get_all_key_pairs, 'name', opts)
 
-    # Delete matching groups
-    delete_aws_resources(aws.get_all_security_groups, 'name', opts)
+        # Delete matching groups
+        delete_aws_resources(aws.get_all_security_groups, 'name', opts)
+    except KeyboardInterrupt, e:
+        print "\nExiting on user command."