Otherwise, the plugin is not able to load kernel modules
(openvswitch, vxlan, vport_vxlan) required by fastdp which
makes weave to fallback to sleeve.
CAP_SYS_MODULE is required in order to load kernel modules.
"docker.sock" is used to access Docker API which is required to:
1. subscribe to Docker events to configure-arp,
2. query Docker network info to detect whether multicast should be
enabled.
3. get list of Swarm peers before starting the plugin.
(1) is currently not implemented.
(2) is replaced by WEAVE_MULTICAST env var which
can enable multicast for all Weave networks created by
the plugin (not ideal, but better than nothing).
(3) is fixed by not removing "restart.sentinel".
Raj Chaudhuri