Chnage delete default_project.

WHen deleting project from account that is using project as
default_project, delete the default_project assignment instead of
deleting the entire account.

Change-Id: I2cb21df9540c5aeab0efb392d6281a4f7d40b5e1
Fix handling if no default_project.

Change-Id: I372ebaa9a94b8e8e712586ef69f3c053aaea1f39