Avoid using 192.168.0.0/16

When using 192.168.0.0/16 address space on a 192.168.x.0/24 NAT'd
network (such as most home routers) VirtualBox will complain that the
virtual private network overlaps with an existing network and refuses to
start the VMs. 10.255.0.0/16 is a less-likely to conflict range, though
not perfect.
Merge pull request #37 from hunner/ip_space

Avoid using 192.168.0.0/16
QE-361 support using a default host in tests

- create a default host
- support using the role as a valid host in calls to #on
  eg, on 'loadbalancer', "echo hello"
- create shell command to run on default host
- provide matchin commands to *_on
- spec tests for new commands, some backfill
review fixes and changes