NanoHTTPD: Clear headers between requests
NanoHTTPD: Clear headers between requests

This bug resulted in socket timeouts on keep-alive connections as
content-length was incorrectly preserved from the previous
request.

nla/tinycdxserver,nla/outbackcdx,nla/outbackcdx,nla/outbackcdx,nla/tinycdxserver,nla/outbackcdx,nla/tinycdxserver,nla/tinycdxserver