LU-2059 mgs: don't fail on missing params log

LU-2059 mgs: don't fail on missing params log

The mgc_process_cfg_log() fails if 'params' log is not
accessinble and has no local copy. In fact that log is
optional and may be just empty.

Patch allows 'params' log to be empty and checks also for
'params' log in other places to avoid wrong error messages.
There was also deprecated code in mgs_write_log_direct_all()
which creates lustre-params log which is not used by anyone now.
Third change is removal of exceptions in conf-sanity.sh and
insanity.sh related to LU-2059

The only exception is insanity test_1 which is still failed due
to other reason.

This patch is back-ported from the following one:
Lustre-commit: 864fc9daac267819f5e3bdebef6cdac4c6325626
Lustre-change: http://review.whamcloud.com/10311

Signed-off-by: Mikhail Pershin <mike.pershin@intel.com>
Change-Id: I081ca3920f3c2d05d4e966ed5234369ddc0eaac0
Reviewed-on: http://review.whamcloud.com/12427
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Hongchao Zhang <hongchao.zhang@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>