- Cleanups

 - Cleanups
 - scst_set_initial_UA() added. It sets initial Unit Attention for session, replacing default scst_sense_reset_UA
 - task_mgmt_affected_cmds_done() callback added in struct scst_tgt_template. It's informs target driver that a received task management fun
ction has been completed.
 - Now devices blocked only in reset TM commands. ABORTs, etc. now done without devices blocking
 - scst_unregister_session_ex() removed, since there are no users of it

git-svn-id: https://scst.svn.sourceforge.net/svnroot/scst/trunk@684 d57e44dd-8a1f-0410-8b47-8ef2f437770f