fix handling of documentRoot and change MaxAge setting to maxAge for consistency
no need to check url in static@tntnet since it is already done before
set max age of files in multi binary components to 4 hours and allow it to be modified using maxAge arg
disable cache if age is set to 0 using the method HttpReply::setMaxAgeHeader
wrong header was set when caching was enabled in the last commit
Merge branch 'master' of https://github.com/maekitalo/tntnet
Add doxygen comment.