Fix specs for digitalocean

[enxebre]

When dpeloying from wercker on Digitalocean:

1. Docker container "weave" should be running
   On host `mesos_masters'
   Failure/Error: it { should be_running }
   MultiJson::ParseError:
   784: unexpected token at 'Error: No such image or container: weave
   []
   '
   /bin/sh -c docker\ inspect\ weave
   Error: No such image or container: weave
   []

https://app.wercker.com/#deploystep/55881a3e9e5d0cdb461345b5

[enxebre]

This need to be tested against after builing the DO image using the latest version of the packer template.

[enxebre]

Weave service is not running and logs showing:
network 10.128.0.0/10 would overlap with route 10.131.0.0/16
Default -iprange 10.128.0.0/10 overlaps with existing route.
Please pick another range and set it on all hosts.

[enxebre]

Think this is because default value for iprange overlaps with default Digitalocean internal subnet. So setting something more restrictive should work like:
${WEAVE} launch -iprange "{{ weave_docker_subnet }}" ${PEERS}
having that:
weave_docker_subnet: 10.2.{{ loop.index }}.0/24

See https://github.com/Capgemini/Apollo/pull/327/files

[tayzlor]

Closing via 5ade856

[wallies]

closing in favour of #583