Modify 8.0's startup script to simulate a full login (su -l) . Also
add support to select login class for running postgresql .
The new startup script, using rc.subr, is now installed for all
versions of postgresql. Bump portrevisions, since startup script is
PR: 78630 
Submitted by: Vivek Khera 
Submitted by: Brian B. 
Approved by: seanc (implicit)