Bug #1006634, part 1

Whenever a new user, group, or portfolio page is created and clean
urls are enabled, ensure the urlid field is set to something vaguely
sensible.  Ensure new user and group urlids are unique, and ensure new
view urlids are unique for the owner.

Change-Id: I2033f5aa1f32650b4fc72666c54c371d05df133c
Signed-off-by: Richard Mansfield <richard.mansfield@catalyst.net.nz>