Add code to accept command line arguments

Accepts command line arguments for path, interested GPIO transition
and an optional systemd unit file to be called into when the GPIO
transitions per expectation.

Change-Id: I98d967d36cfbb768bc9d0dd04517575fa7e408fe
Signed-off-by: Vishwanatha Subbanna <vishwa@linux.vnet.ibm.com>
6 files changed