BibSched: many improvements

* Displays a Yes/No box to make sure you don't delete tasks by mistake.

* In the bibsched daemon, every 50 cycles, check for local tasks that have
  crashed.

* Store debug mode in database so that we can switch it on and off without
  restarting the bibsched daemons.

* Fixes a bug that would mark a task as crashed because the pid of that
  task would not exist anymore but because the task has completed properly.

* Press B to lood bibsched.log in your pager.

* Fixes the task options panel when a task has a very long list of arguments.
  (closes #1177)

* Tasks in about to stop are not going to sleep as soon as possible anymore.
  This proved annoying because instead of stopping they would just wait in
  SLEEPING and you would have to wake them up manually in order to make them
  stop.

* Adds a help panel in the bibsched monitor accessed via the "h" keystroke.

* Limits the progress column char length to match the database schema

* Adds the username of person doing the action in bibsched when running
  a task manually or editing the motd

* Adds --host which allows to force the execution of a task to a
  certain host (closes #991)

* Prevents non concurrent task to wake up too early, prevent higher priority
  tasks to run.

* flush logs after writing each message.
  This can be useful when using a filesystem that buffers yours writes
  like AFS and want to check the logs from a different server than the one
  the task is running on.

* Confirmation dialog before deleting periodic tasks

* Bind signal USR2 to starting foo remote console
  to debug running bibtasks.

* If you ask a task to stop, (status is set to "ABOUT TO STOP") and then you
 lower the priority of the task, say to -11, the scheduler changes the status
 of the task to "ABOUT TO SLEEP", ignoring the previous status.

* When --fixed-time is set and a task is postponed we used the regular
  sleeptime (to respect the fixed time) instead of running as soon as possible
  (in this case the beginning of the allowed times by --limit)
  e.g. A task is scheduled to run between monday and friday and sleep 24 hours
       and is supposed to run at 7am.
       Old behavior, on saturday 7am, it is postponed to run on monday morning
       at midnight.
       New behavior, it is postponed to run sunday, 7am. On sunday it is
       postponed to monday 7am.

* Fixes a bug sleeping a monotask that needs to run instead of
  ourselves.

* Adds STOPPED to displayed status in default bibsched view

* Removes the ability to force run manually tasks via the bibsched
  monitor and out of their time limit (specified via -L 00:40-05:00)

Signed-off-by: Alessio Deiana <alessio.deiana@cern.ch>
Reviewed-by: Samuele Kaplun <samuele.kaplun@cern.ch>

config/invenio.conf

@@ -1440,6 +1440,12 @@ CFG_BIBSCHED_INCOMPATIBLE_TASKS = ()
 ## If path is relative, CFG_LOGDIR will be joined as a prefix.
 CFG_BIBSCHED_LOGDIR =
 
+## CFG_BIBSCHED_FLUSH_LOGS -- flush logs after writing each message.
+## This can be useful when using a filesystem that buffers yours writes
+## like AFS and want to check the logs from a different server than the one
+## the task is running on.
+CFG_BIBSCHED_FLUSH_LOGS = 0
+
 
 ###################################
 ## Part 12: WebBasket parameters ##