Updating API parameter documentation (refs #1901)

Removed unused parameters.
More docs for the "list" command.
Use only the first line of the parameter documentation in "arv resource help".
Clients use $HOME/.config/arvados/settings.conf for configuration. (fixes #1943)
Merge branch '1943-client-sdk-config-files'

Conflicts:
	sdk/python/arvados/__init__.py