Exception in ProcessResource collector

[hvnsweeting]

I'm using latest version of diamond installed from pip

$ diamond --version
Diamond version 4.0.515

Got exception

1501479599.29	[ProcessResourcesCollector:20455:ERROR]	/tmp/py2/local/lib/python2.7/site-packages/diamond/utils/scheduler.py:99
Traceback (most recent call last):
  File "/tmp/py2/local/lib/python2.7/site-packages/diamond/utils/scheduler.py", line 73, in collector_process
    collector._run()
  File "/tmp/py2/local/lib/python2.7/site-packages/diamond/collector.py", line 477, in _run
    self.collect()
  File "/tmp/py2/share/diamond/collectors/processresources/processresources.py", line 198, in collect
    self.collect_process_info(process)
  File "/tmp/py2/share/diamond/collectors/processresources/processresources.py", line 178, in collect_process_info
    pi = process_info(process, self.config['info_keys'])
  File "/tmp/py2/share/diamond/collectors/processresources/processresources.py", line 78, in process_info
    process_info = process.as_dict(info_keys)
  File "/tmp/py2/local/lib/python2.7/site-packages/psutil/__init__.py", line 552, in as_dict
    ", ".join(map(repr, invalid_names))))
ValueError: invalid attr name 'memory_info_ex'

Seem caused by new version of psutil removed the memory_info_ex

>>> psutil.version_info
(5, 2, 2)
>>> psutil.Process().as_dict().keys()
['status', 'cpu_num', 'num_ctx_switches', 'pid', 'memory_full_info', 'connections', 'cmdline', 'create_time', 'ionice', 'num_fds', 'memory_maps', 'cpu_percent', 'terminal', 'ppid', 'cwd', 'nice', 'username', 'cpu_times', 'io_counters', 'memory_info', 'threads', 'open_files', 'name', 'num_threads', 'exe', 'uids', 'gids', 'cpu_affinity', 'memory_percent', 'environ']

The memory_info_ex introduced in 4b8b13f#diff-06a2be2c3ff6b70d9d12032be5653241R14

For now, to workaround, I just remove memory_info_ex from info_keys config of the collector.

[shortdudey123]

Feel free to submit a PR.