Add option to list disabled plugins

After disabling a plugin, it can now be viewed in the ls command by
specifying the --all (-a) argument.  This will be more useful once
we add an ssh command to re-enabled plugins which are disabled.

Change-Id: I4100cd9df4ebfac87b2099ef2c916b99ef55c978
Signed-off-by: Brad Larson <bklarson@gmail.com>
3 files changed