Add vol_min/vol_max; Substring title before sending it to Pebble, just in case it's more than the max AppMessage buffer size.

Long hold (700ms) up button now sets the volume to max.
Long hold (700ms) down button now sets the volume to 0.
Use PebbleKitJS Configuration to set options.

* New: Set VLC server host and password via Pebble app.
* New: Store VLC server host and password in persistent storage.
* Fix: Destroy all the images in exit.