Ordering admins user classes by uid.

I left the non standard uids at the top of the file, so it is
easy to append to the bottom of the file and increment uid when
adding a new user.

Just to be sure I didn't accidentally delete anyone:

Before this commit:
$ grep 'class.*inherits baseaccount' admins.pp  | wc -l
     125

After this commit:
$ grep 'class.*inherits baseaccount' admins.pp  | wc -l
     125

Change-Id: Iaaa473ff9a8c0ce4da582cb97c682f39d50e7a4e