ovn: Fix some split db issues in ovn-ctl.

ovn: Fix some split db issues in ovn-ctl.

The default location for databases should be $dbdir, not $rundir.

The default location for log files comes from $logdir, not $OVS_LOGDIR.

Fix ovs-appctl commands.  The code assumed that passing
--unixctl=ovnnb_db was sufficient to allow an argument of "-t ovnnb_db"
to ovs-appctl.  Unfortunately, that's not the case.  This literally
results in a unix socket called "ovnnb_db" and ovs-appctl will look for
one in the form "onnb_db.PID.ctl".  For now, add ".ctl" to the name and
pass it by full path to ovs-appctl.  In the future, it would be even
better to have an option similar to --unixctl that specifies a prefix
for ".PID.ctl", as I believe that would give the behavior we want.

Reported-by: Gurucharan Shetty <guru@ovn.org>
Reported-at: http://openvswitch.org/pipermail/dev/2016-March/068498.html
Fixes: 60bdd01148e4 ("Separating OVN NB and SB database processes")
Signed-off-by: Russell Bryant <russell@ovn.org>
Acked-by: Gurucharan Shetty <guru@ovn.org>