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_git_test.py b/bisect_git_test.py
index 1974007..24d1d07 100644
--- a/bisect_git_test.py
+++ b/bisect_git_test.py
@@ -23,7 +23,7 @@
 
   def test_basic(self):
     """Tests basic functionality."""
-    bisector = cli.BisectorCommandLineInterface(bisect_git.GitDomain)
+    bisector = cli.BisectorCommandLine(bisect_git.GitDomain)
 
     start = 12345678000
     fake_commits = map(str, range(start, start + 10))