Take a tag not a string
firewaller.Unit takes names.Tag
firewaller.Machine takes names.Tag
firewaller.Machine takes names.Tag
more string -> Tag conversions
Move string -> Tag conversions.
More string -> names.Tag work
Merge branch 'master' of https://github.com/juju/juju into 114-state-accessors-take-tags
Merge branch '115-state-string-tags' into 114-state-accessors-take-tags
Use concrete types rather than names.Tag interface
fix todo
client side of NetworkInterfaceWatcher
Merge remote-tracking branch 'upstream/master' into 121-networkinterfaceswatcher
change StringsWatcher to NotifyWatcher
Add new proof of access put logic
Merge remote-tracking branch 'upstream/master' into 121-networkinterfaceswatcher
Merge remote-tracking branch 'upstream/master' into 121-networkinterfaceswatcher
Merge remote-tracking branch 'upstream/master' into 121-networkinterfaceswatcher
Reaplaced os.Symlink and os.Readlink

symlinks are not supported by standard go os package on windows. Replaced all instances of os.Symlink and os.Readlink with the implementation in github.com/juju/utils/symlink. On linux these functions simply call os.Symlink and os.Readlink. On windows they use our implementation
Various test tweaks, code review fixes