use Proc::ProcTable rather than ps and pgrep

use Proc::ProcTable rather than ps and pgrep

Rather than spawn off repeated shell calls to ps
and pgrep when running osrf_control --diagnostic
or --kill-with-fire, use Proc::ProcTable.  This
should result in better portability, and also runs
faster.

For example, prior to this patch, osrf_control -l --diagnostic
resulted in the following timing:

real    0m2.981s
user    0m1.152s
sys     0m2.284s

With this patch:

real    0m0.884s
user    0m0.580s
sys     0m0.328s

New Perl dependencies are:

  Proc::ProcessTable
  DateTime::Format::Duration

Signed-off-by: Galen Charlton <gmc@esilibrary.com>