[BUG] Lv2 Plugins are not detected after a plugin is installed.

[rerdavies]

See discussion #118

There are two separate issues.

1. The web client does not reload plugin information after reconnecting, and thus fails to detect new plugins when the service restarts.
2. The services scans for new plugins once at load time, but doesn't monitor for new plugins after that.

The first is trivial to fix.

The second is less trivial, but should be done to avoid an unfortunate user experience. Probably check and rescan when the plugin dialog reloads.