If the overhead of determining the hostlist for a given task list
is too high, then report a hostlist of "Unknown" instead. If the
overhead is too high, then srun will become unresponsive and communications
will timeout/fail.
bug 3044

Modify srun task completion handling to only build the task/node string for
    logging purposes if it is needed. Modified for performance purposes.
bug 3044

Add get_log_level() function to return the highest LOG_LEVEL_* used
for any logging mechanism.

This reverts commit 1ec2a4ae.

Conflicts:
	src/api/step_launch.c

Bug 3063.

In scontrol show nodes.

Restructure srun command locking for task_exit processing logic for improved
  parallelism. This change decreases the amount of time consumed by serial
  logic by 2 orders of magnitude.
bug 3044

Grab federations from db at startup instead of waiting for db_update and
load from state if the db is down.

Instead of making a separate copy. All of the cluster_recs are now in
the federation_rec with a pointer to the local cluster rec.

Select federations base off which clusters belong to them.

Preserve node "RESERVATION" state when one of multiple overlapping
    reservations ends. Previous logic would clear the node's
    RESERVATION state flag when any one of the reservations on the
    node ended rather than keeping the node in RESERVATION state
    until the last reservation ended.
bug 3057

The logic is now heavier weight, so increase interval between tests
  from 2 to 5 seconds

Instead of making copies just use the pointers and stay in the read
locks.

Before fixing fed.flags to be initialized to FEDERATION_NOT_SET, the
federation's flags were being set to 0 when a federation modification
happened.  These tests verify that the flags stay after a federation
modification.

Was modeled after cluster adding where commit the check was being done
before sending the changes to the dbd. But since the dbd isn't making
any additional tables for federations -- like it does for clusters -- it
can send to the dbd first and make sure they worked and then ask to
commit the changes.

Ran into the issue after initializing fed flags to NOTSET. Fed flags
were always being set to 0 on modification.

Changed READ_LOCK to WRITE_LOCK since we are updating the node's select
info (select_g_select_nodeinfo_set_all).

Inside locks.

Also fixes setting weight at cluster creation.