remove misleading comment...
attach() and detach() are never invoked directly,
plus it's really not that hard to figure out what they do.
make with_container_netns take the container as the first arg
and invoke the subsequent command.
This is closer to typical 'with' semantics.
refactor: don't extract param to var and shift unless we have to
refactor: it's not an IPADDR but a CIDR
refactor: remove add_nat_rule
it did too little to be worthwhile
refactor: simplify 'attach'
Move the interface into the container network NS asap, which
simplifies error handling.
refactor: simplify multicast route addition in 'attach'
Merge pull request #152 from rade/weave_script_tidy

various simplifications and tidying up in weave script