pgsql: Update /contrib OS/X startup files, and move to a separate OS/X

Log Message:
-----------
Update /contrib OS/X startup files, and move to a separate OS/X
directory.

Mark Cotner and David Fetter

Added Files:
-----------
    pgsql/contrib/start-scripts/osx:
        PostgreSQL (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/start-scripts/osx/PostgreSQL?rev=1.1&content-type=text/x-cvsweb-markup)
        README (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/start-scripts/osx/README?rev=1.1&content-type=text/x-cvsweb-markup)
        StartupParameters.plist (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/start-scripts/osx/StartupParameters.plist?rev=1.1&content-type=text/x-cvsweb-markup)
        install.sh (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/start-scripts/osx/install.sh?rev=1.1&content-type=text/x-cvsweb-markup)

Removed Files:
-------------
    pgsql/contrib/start-scripts:
        PostgreSQL.darwin
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/start-scripts/PostgreSQL.darwin)
        StartupParameters.plist.darwin
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/start-scripts/StartupParameters.plist.darwin)