* Winchester discs can take a long time to spin up which results in
   blockd also taking a while to complete to start.

 * Make sure uvol only gets started once blockd is ready.

 * Clean up paths (use '/tmp/run/uvol' everywhere instead of relying on
   the '/var' -> '/tmp' symlink)

 * Create 'apk' folder when initializing .meta volume.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

Fix bring-up of ro volumes on creation and on boot.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

Emmit ubus events when volumes come up/down.
Make sure volume state is always well defined by introducing
additional state 'write-prepare' (wp) during mkfs.
Add init scripts to bring up volumes at boot.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>