[server,client] Use a <request-method> class for request methods.
[tests] Tag tests that use the internet with 'online'.
[tests] Add comment about conflicting-listener-ips-test being expected to fail.
[server,client,common] Use <byte-string> instead of <symbol> for http version.
[server] Set *log-content?* to #f by default.
[server] Use constants for request methods.
Merge pull request #74 from cgay/no-symbols

Don't use <symbol>s for http-version or request methods.