This is partial revert of 5ca6e6fc9cb2403307114877ece24e394be35794 .
After discussing several problems caused by scope separation, we
decided to suspend implementing the scope enforcement and focus on
project personas like reader role. As the result of that decision,
the system admin persona will be removed, thus we should use
the project admin persona instead. The previous policy rules to allow
system scope access have been reverted by [1].
[1] 755a1503187a29f9b4f6ecbf369acb781c3e95e7
Change-Id: I52f81faf2008e6d8c152503ca2d706fd962b8ed3
a6dd3edfe3