bisect-kit: fix pylint errors

Besides normal fixes, BisectorCommandLineInterface is renamed to
BisectorCommandLine. Although new version of pylint no longer complain
interface-not-implemented (instead, saying the disable option is
undefined), chromite and depot_tools still use the old one. Renaming is
easier to avoid the annoyingness.

BUG=chromium:776314
TEST=cros lint *.py bisect_kit/*.py

Change-Id: I4cf3f63ee950d913a6b3f5b6a7a7b59810066963
Reviewed-on: https://chromium-review.googlesource.com/987660
Commit-Ready: Kuang-che Wu <kcwu@chromium.org>
Tested-by: Kuang-che Wu <kcwu@chromium.org>
Reviewed-by: Kuang-che Wu <kcwu@chromium.org>
diff --git a/bisect_kit/util.py b/bisect_kit/util.py
index 35306b8..1618e13 100644
--- a/bisect_kit/util.py
+++ b/bisect_kit/util.py
@@ -116,7 +116,7 @@
     for proc in psutil.Process(self.p.pid).children(recursive=True):
       try:
         proc.terminate()
-      except psutil._error.AccessDenied:  # pylint: disable=protected-access
+      except psutil.AccessDenied:
         logger.warning('Unable to terminate pid=%d; ignore', proc.pid)
     try:
       self.p.terminate()