Produce benchmark JSON schema v2

- No more '(Display)' strings in the GPU names, but store devices as
  `{'name': name, 'type': 'CPU/CUDA/OPENCL', 'is_display': bool}`
- Introduces testing with py.test & pipenv. The test suite is far from
  complete, though.

.coveragerc

@@ -0,0 +1,4 @@
+[run]
+omit =
+    # omit 3rd party modules
+    benchmark/foundation/third_party/*