Add INPUT ACCEPT rule for --nat-local connections

Add INPUT ACCEPT rule for --nat-local connections

When using the --nat-local argument on the fwknop client command line, the
fwknopd server needs to add an INPUT ACCEPT rule for the requested access
since the incoming connection is destined for a local socket.  Added test
suite support to test --nat-local access.

[test suite] Minor bug fix to ensure that all file_find_regex() calls return
true if all regex's are matched and false if any regex does not match data in
the specified file.