Provide better error message for aggregate-create

For an InvalidAggregateAction exception:
Before: 'ERROR: There was a conflict when trying to complete your request (HTTP 409)'
After: 'ERROR: Cannot perform action 'create_aggregate' on aggregate 'N/A'. Reason: invalid zone. (HTTP 400)'

docImpact

Fix bug 1083353

Change-Id: I26e30059fe5bbc30eecc52cccec4eba2a57d00db
(cherry picked from commit 4e43747037058522087e6eb71ef3bcce266d55cc)
Fix errors in used_limits extension

Fixes bug #1062049

There was a typo mapping the security groups resource to floating IPs.

Key pairs don't work with the extension because of bug #1089877.

(cherry picked from commit 6c9d9ab)

Change-Id: Ifd694b21fef1dc95e67c07dcef0cd6ea3daa8d53
Add an iptables mangle rule per-bridge for DHCP.

When vhost-net is present on a host, and DHCP services are
run on the same system as guests (multi_host), an iptables
rule is needed to fill packet checksums.  This adds a rule
per-bridge for multi_host networks when vhost-net is present,
similar to how newer versions of libvirt handle the issue for
bridges/networks that it manages.

Fixes LP: #1029430

EDIT: Updated tests and pep8.

(Backported from commit 901a3dacb6f2d36cbe8d23707dba75452e91df33)

Change-Id: I1a51c1d808fa47a77e713dbfe384ffad183d6031
Limit formatting routes when adding resources

By default, routes.mapper.Mapper.resource adds a bunch of formatted
routes that accept anything after a '.'. Our spec says only .xml
and .json are accepted so limit the formatting to those valuse.

This allows identifiers with a '.' in urls. A few tests were added
to the extensions test to prove that .xml and .json are stripped
but other values are not.

Fixes bug 1027788

Change-Id: Ic888aa5d75050d6b14763c2a787ac8c8d5ab1f69
(cherry picked from commit 8935c3bde9e9635f65522488c1aca5df5b03050d)
Merge "Fix errors in used_limits extension" into stable/folsom
Merge "Limit formatting routes when adding resources" into stable/folsom
Merge "Provide better error message for aggregate-create" into stable/folsom