Do not call deprecated `psutil` functions

Fix #28
Thanks, @rhcarvalho
Monitoring returns only available memory info

It was trying to return some "keys" in namedtuple that are not present in all
operating systems.
Use <namedtuple>._asdict() method.

See discussion in https://github.com/NAMD/pypelinin/commit/5efe6f6ea2b#commitcomment-2710257
Replace `OrderedDict` with `dict` (monitoring)
Merge branch 'bugfix/psutil-deprecated-methods' into develop