This adds support for only allowing normal users with account age
equal or greater than a "waiting period" threshold to create streams;
this is useful for open organizations that want new members to
understand the community before creating streams.
If create_stream_by_admins_only setting is set to True, only admin users
were able to create streams. Now normal users with account age greater
or equal than waiting period threshold can also create streams.
Account age is defined as number of days passed since the user had
created his account.
Fixes: #2308.
Tweaked by tabbott to clean up the actual can_create_streams logic and
the tests.
rht
vaibhav