coveralls: exclude protocols via .coveragerc and use it for travis

All protocol classes are abstract interfaces which are do not need to be covered
by tests. Exclude them in .coveragerc and use it during the travis run.

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>

.coveragerc

@@ -0,0 +1,10 @@
+[report]
+exclude_lines =
+    pragma: no cover
+    def __repr__
+    if self.debug:
+    if settings.DEBUG
+    raise AssertionError
+    raise NotImplementedError
+    if 0:
+    if __name__ == .__main__.:

.travis.yml

@@ -7,6 +7,6 @@ install:
   - pip install -r dev-requirements.txt
   - pip install -e .
 script:
-  - pytest --cov=labgrid
+  - pytest --cov-config .coveragerc --cov=labgrid
 after_success:
   - coveralls