Implement shell

All it does right now is start a bash shell.  Allowing the user to specify
commands is todo.

Note that this requires use of recent github.com/lxc/lxc git tree, specifically
commit 62183f1af.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Implement List

The output format is clearly not what we'll want for the final version,
but with this the supported command set makes lxd actually useful:

create
list
start
attach
stop
delete

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Merge pull request #24 from hallyn/list.1

List.1