CI: install pytest and fix coverage configuration

Author: tacaswell

.coveragerc

@@ -0,0 +1,11 @@
+[run]
+branch = true
+source =
+    mplaltair
+
+[report]
+exclude_lines =
+    raise NotImplemented
+    def __str__
+    def __repr__
+    if __name__ == .__main__.:

.travis.yml

@@ -18,11 +18,11 @@ matrix:
 
 install:
   - python -m pip install --upgrade pip
-  - python -m pip install --upgrade codecov coverage
+  - python -m pip install --upgrade codecov coverage pytest
   - python -m pip install -ve .
 
 script:
-  - coverage run python -m pytest
+  - coverage run run_tests.py
   - coverage report -m
   - set -e
   - codecov

run_tests.py

@@ -0,0 +1,6 @@
+#!/usr/bin/env python
+import sys
+import pytest
+
+if __name__ == '__main__':
+    sys.exit(pytest.main(sys.argv[1:]))