Merge duplicated --tcp option help text for lxd command

Signed-off-by: Hiroaki Nakamura <hnakamur@gmail.com>
Merge pull request #104 from hnakamur/merge_lxd_tcp_help_text

Merge duplicated --tcp option help text for lxd command
Actually return a 404 for a missing container

NewContainer always returns a new container (unless some internal LXC error has
happend), even if it is not defined yet. In some cases, we only want to allow
operations on containers that exist, so we should check and be sure the
container is defined before we try to perform operations on it.

Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Merge pull request #106 from tych0/return-404

Actually return a 404 for a missing container
Merge pull request #105 from stgraber/master

image-handling: Properly escape html looking tags
rest-api: Update background operations

Return the metadata dict on creation and allow storing multiple related
resources.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>