BUG/MINOR: lua: schedule socket task upon lua connect()

BUG/MINOR: lua: schedule socket task upon lua connect()

The parameters like server-address, port and timeout should be set before
process_stream task is called to avoid the stream being 'closed' before it
got initialized properly. This is most clearly visible when running with
tune.lua.forced-yield=1.. So scheduling the task should not be done when
creating the lua socket, but when connect is called. The error
"socket: not yet initialised, you can't set timeouts." would then appear.

Below code for example also shows this issue, as the sleep will
yield the lua code:
  local con = core.tcp()
  core.sleep(1)
  con:settimeout(10)