Refined schema for VPCZoneIdentifier

The schema now says it is a list of strings. Also upgraded the
description.  Also clarified the name of
test_invalid_vpc_zone_identifier.

Change-Id: I4b17dbd146965df3df3f4205dddafc0b65061294
Closes-Bug: #1294717
Support proxying Heat API by using x-forwarded-for header

Adding 'X-Forwarded-For' header support to enable  Heat API
proxying

Implements: blueprint proxying-heat-api
Change-Id: I36a0d3dd3f672a485c4a9c0cd541b705033e9025
Merge "Refined schema for VPCZoneIdentifier"
Merge "Support proxying Heat API by using x-forwarded-for header"