mon: use kill instead of pkill in osd-pool-create

The --pidfile option of pkill is not supported by all versions. Use kill
instead for compatibility. Instead of looping on : loop on sleep 1 so an
inifinite loop does is slower at filling the disk.

Signed-off-by: Loic Dachary <loic@dachary.org>
Merge pull request #985 from dachary/wip-erasure-code-defaults

mon: use kill instead of pkill in osd-pool-create

Reviewed-by: Joao Eduardo Luis <joao.luis@inktank.com>