pginstaller - pginst: Remove the CheckUserIsAdmin() check.

Log Message:
-----------
Remove the CheckUserIsAdmin() check. this is no longer needed now that pg_ctl can shed user rights at startup, thus allowing us to safely run under an admin account.

Modified Files:
--------------
pginst/ca:
pginstca.c (r1.95 -> r1.96)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/pginst/ca/pginstca.c.diff?r1=1.95&r2=1.96)
user.c (r1.19 -> r1.20)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/pginst/ca/user.c.diff?r1=1.19&r2=1.20)