Update README.md
Added bounds checking for listening_ports.
Needs to be a valid TCP port number, and not less than 1 or greater than 65535
support serving pre-gzipped files transparently provided the user agent accepts gzip content-encoding. The feature breaks if the user agent makes a range request within a gzipped file, and returns 501 in this case
Merge pull request #176 from codyhanson/portRangeFix

Added bounds checking for listening_ports.
Merge pull request #177 from arvidn/master

support serving pre-gzipped files