pycheckpatch script to run checkpatch.pl on a list of commits

The script takes same arguments as "git rev-list". With an optional "-a"
argument, it lists all commits with pass/fail status.

Signed-off-by: Malahal Naineni <malahal@us.ibm.com>
Acked-by: Venkateswararao Jujjuri (JV) <jvrao@linux.vnet.ibm.com>