fixes issue #11
add mrbgem.rake
remove makefile.
cleanup rake file.
workaround for bits older version of libuv.
don't use static class instances
implementation of addrinfo.
add sin_addr/sin_port.
add UV::Thread.
add UV::Barrier.
add TODOs.
support for build with external libuv sources
add extern for environ.
initialize by NULL.
fixed type check for port number.
remove check of writable.
add SIGPIPE.
handle SIGPIPE.
update rakefile.
use <<.