Fix CLI help message for project info/modify

Problem: a new-line was missing, causing the first line of the details
to break.
Merge quota info to quota list (commands)

Side effect: class _quota is not needed, therefore merged to
quota_list as well
Implement BooleanArgument

BooleanArgument is different to FlagArgment because it accepts
both boolean values (True|False)
Change --private argument in project create/modify

In create: change argument from Flag to Boolean
In modify: add a --public Flag argument
In arguments: test BooleanArgument and fix minor bugs