Add sleep to posix library startup to avoid race. Closes #857

* On win32 we can get the target control port instantly and immediately connect
  before program startup, on posix systems we must wait until afterwards and
  poll for open sockets.
* This means there's a small window of opportunity where the program may have
  started running but we haven't connected yet to send any initial commands.
  Adding a sleep should give target control time to connect.