adding http transport

Although the new API breaks compatibility with previous version they
are very close. In the previous API:

  t = LeelaClient::Api.transport(["localhost:6968"])
  t.send([...])

The port could be provided in the string itself. This is no longer, as
we now have two protocols:

  t = LeelaClient::Api.transport(["localhost"])
  t.send([...], :method => :udp, :port => 6968)
  t.send([...], :method => :http, :port => 4080)
v1.0.0