#155 hide options on user edit when lacking privileges

[Robert Treat]

I found bug in phpPGAdmin, I'm not able change privilege to any role.
Main problem there is that I'm not superuser, but I have create role
privilege. However when I try to modify any user account phpPgAdmin
sends command also with NOSUPERUSER option which fails see:

postgres=> alter user pokus nosuperuser;
ERROR: must be superuser to alter superusers

By my opinion phpPgAdmin should detect if I'm not superuser and do not
offer this checbox.

Zdenek