Adapt to psutil 2.0.0 API.

API changed.
https://psutil.googlecode.com/hg/HISTORY

Tested with 0.5.1, 1.2.1, 2.0.0
Fix python trying to use default getattr using psutil 0.5.1.

Don't know why adding "None" as second default helps.
Fix error types.
Fixed psutil 0.5.x support on Windows
Merge pull request #337 from regdoug/windows-psutil-0.5

Fixed psutil 0.5.x support on Windows
Merge pull request #336 from herr-biber/adapt-to-psutil2.0.0-api

Adapt to psutil 2.0.0 API.
PsUtil 2.0 is back for the branch 1.x
Merge pull request #335 from weaselkeeper/master

Implement toggle of process list display
Add z key in the documentation
Fix case.
Merge pull request #338 from herr-biber/master

Fix case.
Fix help screen in 80x24 terminal size

Add new z key in man page
Correct a regression with client/server for PsUtil 1/2
Merge branch 'master' of github.com:nicolargo/glances