Administrators can use these commands to view loaded plugins, install
new plugins from any URL source the server can reach (including HTTP),
and disable plugins that might not required or are misbehaving.
When installing plugins the JAR can be supplied as stdin to the SSH
command, or as a URL. Either way the server copies the JAR into a
temporary file in the $site_dir/plugins directory, then safely does
a reload of the plugin by stopping the running plugin, replacing the
JAR on disk, and then starting the plugin back up. This is safer than
the rescan thread detecting changes made in the background.
Removing a plugin doesn't actually delete it, rather the plugin will
be renamed to have a ".disabled" suffix, preventing the scanner from
considering that plugin during a future server restart.
Change-Id: Iaa4cb9d7c28294fa616975093a0d4ffb1fcb2788
5a99e04ccf