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.

benchmark/foundation/system_info.py

@@ -2,6 +2,7 @@ import json
 import platform
 import subprocess
 import sys
+import typing
 
 from datetime import datetime
 
@@ -10,9 +11,12 @@ from .third_party import cpuinfo
 from .third_party import cpu_cores
 from .third_party.dateutil import parser
 
+from . import context
+
+
+def _getBlenderDeviceInfo(ctx: context.Context) -> typing.List[dict]:
+    prefix = "Benchmark Devices: "
 
-def _getBlenderDeviceInfo(ctx):
-    PREFIX = "Benchmark Devices: "
     command = [ctx.blender,
                "--background",
                "--factory-startup",
@@ -28,8 +32,8 @@ def _getBlenderDeviceInfo(ctx):
     stdout, stderr = process.communicate()
     lines = stdout.decode().split("\n")
     for line in lines:
-        if line.startswith(PREFIX):
-            return json.loads(line[len(PREFIX):])
+        if line.startswith(prefix):
+            return json.loads(line[len(prefix):])
     return []