commands/process: write result in the end

Running additional processors will generate new metrics and artifacts.
Update the serialized metadata with the new artifacts/metrics after
running all processors.

wa/commands/process.py

@@ -22,6 +22,7 @@ from wa.framework.output import RunOutput
 from wa.framework.output_processor import ProcessorManager
 from wa.utils import log
 
+
 class ProcessContext(object):
 
     def __init__(self):
@@ -29,6 +30,7 @@ class ProcessContext(object):
         self.target_info = None
         self.job_output = None
 
+
 class ProcessCommand(Command):
 
     name = 'process'
@@ -134,4 +136,5 @@ class ProcessCommand(Command):
             pm.export_run_output(pc)
             pm.finalize()
 
+            run_output.write_result()
             self.logger.info('Done.')