fixed sql-hash which didnt print md5 strings correctly (printed 9
instead of 09)

 * also reorganized a bit and and added a force parameter to migrate
 * dropped unique constraint so that forcing works correctly
 * Add default migrations to handle renaming the MD5s that might be
   extant

re ADWolf:#1156 (1)
sql-hash is now %sql-hash and should just be used by instantiating a
migration object

re ADWolf:#1156
fixed broken escaping when fixing md5s re ADWolf:#1156 (1)