LU-1214 ptlrpc: start minimum service threads

If the ptlrpc_min_threads parameter is changed via /proc after the
service has started, then at least the requested number of service
threads should be started.  Otherwise this parameter would only be
used at initial thread startup and ignored if changed via /proc.

Fix conf-sanity.sh test_52[ab] to verify that at least the minimum
number of threads has been started when threads_min parameter is
changed, instead of just checking the parameter itself.  Also fix
test code style for 80-column line wrapping and tabs for indents.

The head utility does not always support shortcut "-1" option. It
should be specified as "-n1".

Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Change-Id: I6e4bb4131d7500a93952b64102f885c76558cab0
Reviewed-on: http://review.whamcloud.com/2876
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>