Add quick way to query for device information without rendering anything

Ideally we need to print those to the console without any extra storage
created, but that's becoming a bit hairy.

benchmark/farm.py

@@ -46,6 +46,10 @@ def configureArgumentParser():
                         help="Do verbose logging",
                         action='store_true',
                         default=False)
+    parser.add_argument('-i', '--system-info',
+                        help="Only dump system info to the screen",
+                        action='store_true',
+                        default=False)
     return parser
 
 ########################################
@@ -316,7 +320,11 @@ def main():
         ctx.device_type = farm_config['device_type']
         ctx.device_name = farm_config['device_name']
         ctx.image_output_dir = images_output_dir
-        ctx.scenes = ctx.listAllScenes(ctx.scenes_dir)
+        # Don't do any scenes when only querying for system information.
+        if args.system_info:
+            ctx.scenes = []
+        else:
+            ctx.scenes = ctx.listAllScenes(ctx.scenes_dir)
         # Print prelmiinary information.
         blender_dvice_info = benchrunner.benchmarkGetDeviceInfo(ctx)
         if not blender_dvice_info['device_type']:
@@ -346,7 +354,8 @@ def main():
         saveResults(ctx, results, results_output_dir)
         return all_stats is not None
     finally:
-        deleteTempDirectory(config, temp_dir)
+        if not args.system_info:
+            deleteTempDirectory(config, temp_dir)
     return True