Updates to work with HSQLDB 2.2.4.

We need the HsqldbLiaison fixes from samskivert 1.8-SNAPSHOT and we have to nix
some hardcoded bogosity in our own tests.

src/test/java/com/samskivert/depot/MigrationTest.java

@@ -74,8 +74,7 @@ public class MigrationTest extends TestBase
         "CREATE MEMORY TABLE PUBLIC.\"DepotSchemaVersion\"(" +
         "\"persistentClass\" VARCHAR(255) NOT NULL PRIMARY KEY," +
         "\"version\" INTEGER NOT NULL," +
-        "\"migratingVersion\" INTEGER NOT NULL," +
-        "UNIQUE(\"persistentClass\"))",
+        "\"migratingVersion\" INTEGER NOT NULL)",
 
         "CREATE MEMORY TABLE PUBLIC.\"MigrationTest$PKMigrationRecord\"(" +
         "\"id\" INTEGER DEFAULT 0 NOT NULL," +