spacemanager: Mover DB schema management to Liquibase

Target: trunk
Require-notes: yes
Require-book: yes
spacemanager: Maintain aggregate columns with database triggers

Moves the logic to maintain aggregate columns in srmlinkgroup and
srmspace from Java code to database triggers. Adds not-null
constraints to several space manager database columns. This may
take a little while to apply on large databases.

Target: none
Require-notes: yes
Require-book: no