ext_scripts: Always use assume_v0 on create

Always use assume_v0 when creating a new volume. Also extend the scripts to take
an extra "origin_size" argument, to be used as the provided v0_size.
mapperd: Support X_TRUNCATE operation
archipelago: Implement volume listing
archipelago: Remove obsolete '-u' option

Remove obsolete '-u' option from Archipelago cli. Since there is no kernel space
part, all Archipelago interactions affect only userspace components.

Using the new blktap infrastructure, during restarts all mapped volumes are
"paused". This allows us to safely perform a full Archipelago restart.
The administrator cannot stop Archipelago when mapped volumes exist, unless the
new '--force' flag is used.
archipelago: Remove obsolete '--pool' argument
vlmc: Validate volume names

Validate volume names. Disallow all volumes:
 * Starting with 'archip_'
 * Ending in '_lock'
 * Ending in '_(hex number){16}'
Docs: Describe archipelago open/close mechanism
docs: Update archipelago packages

Update archipelago packages and installation procedure.
docs: Update archipelago config section
docs: Add archipelago v0.4 upgrade notes
docs: Remove numbers from sections
docs: Fix design doc index
docs: Update garbage collection design doc
docs: Separate install and admin's guide

Separate installation and administrator's guide.
Also include minor documentation fixes.