trivial: fix yapf/pep8 interaction failing on logical operator

This adds a custom yapf config file with
split_before_logical_operator knob set to false so that
pep8 doesn't complain when:

    if (save_location and save_location != os.path.sep and
            save_location.endswith(os.path.sep)):

is wrongly converted to:

    if (save_location and save_location != os.path.sep
            and save_location.endswith(os.path.sep)):

This keeps the and on the first line as in the first example.

Change-Id: Ibf2813c3c969fd5f1cfd14936f3fecc9100283f7

.style.yapf

@@ -0,0 +1,5 @@
+[style]
+based_on_style = pep8
+spaces_before_comment = 2
+column_limit = 79
+split_before_logical_operator = false

tox.ini

@@ -24,7 +24,7 @@ basepython = python3
 deps =
     -r{toxinidir}/test-requirements.txt
 commands =
-    yapf --style=pep8 -ir {toxinidir}/pegleg {toxinidir}/tests
+    yapf -ir {toxinidir}/pegleg {toxinidir}/tests
 
 [testenv:pep8]
 basepython = python3