Handle booleans from vCloud as strings

Vcloud & Fog wind up returning all boolean values as strings. We
need to account for this.
Handle 1.5/5.1 API deprecated Port/SourcePort attributes

In vCD 5.1 we see the following behaviour respective of the deprectation
of Port and SourcePort (in FirewallRuleType):

* If SourcePortRange is non-decimal (eg a Range, or Any), then
  SourcePort is '-1' (which as per the docs is 'any port', though
  we suspect means 'ignore' in this case)
* Same for DestinationPortRange and 'Port'.

* If SourcePortRange is a single port number, then SourcePort will be
  the same number (eg SourcePortRange = '22', implies SourcePort = '22'.

This is how it is returned by get_edge_gateway from the API. It is not
required that each is specified in post_configure_edge_gateway.
preliminary FirewallService diff, provided by HashDiff
auto-load the ConfigurationGenerator classes
fixing integration tests

ordering tests, so that firewall is resetted only at the start/end of
main context