Removed some non-ANSI-C strftime format strings ("%F") and
locale-dependent formats ("%c") from NSE scripts and libraries.
C99-specified %F was noticed by Alex Weber
(http://seclists.org/nmap-dev/2013/q2/300)
This is the default and can be omitted. Seeing as the value of this
argument was "hardmatched" in 100% of cases, we're better off pretending
the parameter doesn't exist.