use python difflib instead of subprocessed diff

Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>
Merge pull request #13 from ignatenkobrain/diff

use python difflib instead of subprocessed diff
use pydoc instead of /usr/bin/less
fix variable name
simplify condition
pydoc needs string, not a list
handle binary diff again
use rpm bindings to find configfiles

Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>
Merge pull request #14 from ignatenkobrain/python

use rpm bindings to find configfiles