close file before renaming

Renaming an open file is not possible on windows
Adds the 'maas-bridge-interface' option to MAAS configuration
	- By default 'eth0' is used, but this fails on some setups like LP: #1271144 when
	using (p1p2, eth2, ..) interfaces.
- Minor fixes according to @wallyworld observations
- Fixed according to @axw comment.
	- For backward-compatibility, network-bridge is an empty string by default "eth0" will be returned.
Cleanup for new names.ActionTag refactor

hide implementation details more, rearrange code layout, simplify
Update the add machine api to accept both environment name and UUID.
Add a method to get the environment uuid from the client api connection.
Update dependencies.tsv
Use the environment uuid instead of the name.
Use the NewAPIClient method from the env command.
Port the plugins to not use EnvName.
Merge pull request #248 from davecheney/128-update-ssh-terminal

Update dependencies.tsv

Fixes https://bugs.launchpad.net/bugs/1337063
Merge pull request #249 from howbazaar/env-cmd-add-machine

Update add machine to use environment UUID

This is the start of the work to hide the EnvName from the environment command base.

This will allow us to specify an environment using either other command line parameters or environment variables to better allow scripts to call juju without having a $(JUJU_HOME)/environments directory.
Renamed doc/planning to doc/contribution.
Changed to plural after review.
Merge pull request #252 from TheMue/rename-doc-planning-to-contribution

Renamed doc/planning to doc/contribution.

Simple renaming of the directory `/doc/planning` to `/doc/contribution`.
SetPreferIPv6Addresses implemented
Merge pull request #254 from dimitern/dummy-provider-ipv6

provider/dummy: Allow IPv6 addresses for instances and storage

Added SetPreferIPv6Addresses() method on the dummy provider
that controls whether to add IPv6 addresses to started
instances and what storage URLs to use (IPv4 or IPv6).
Also sets the network.PreferIPv6 flag, which influences
addresses selection to prefer IPv6 addresses when available.
Rename HydrateActionTag to JoinActionTag

update names dependencies
Merge branch 'master' into actiontag-refactor