iceweasel wrapper should launch iceweasel, not firefox

[geofft]

Once you solve #1078, you'll notice that /usr/bin/iceweasel.debathena sets moz_progname to firefox and calls firefox.debathena-orig several times. (Depending on exactly how you solved it, you will probably notice because firefox.debathena-orig execs iceweasel.)

We should probably set moz_progname based on $(basename "$0") or so. In any case, we should be calling "$moz_progname".debathena-orig