When running in the AWSVPC mode, we need to do the following:
- Keep the HW TX offloading on.
- Check that the allocated address belongs to the default subnet,
because only one subnet is allowed and it should be the default one.
If it is not possible to determine whether AWSVPC is on, we ignore
all the steps, because the attachment routines have to work
regardless whether the router is running and the AWSVPC detection
is done by querying the /ipinfo/tracker endpoint served by
the router.
Now it's off by default, and there is an option to enable the
multicast route per-network.
We turn it on for the `weave` network created when we start the plugin.
Note that we remove the ability to set the weavemesh network name, or
disabling it altogether. This was always poorly support, since the
removal operation only ever operated on the default name. The option
was also not listed in the usage, though it was in the docs.
Matthias Radestock