- When 'getent hosts localhost' returns '::1' the creation of the
  listener fails because of the port parsing which uses ":" as a
separator
- Use of net.SplitHostPort() to do the job
- Adding unit tests to ensure that the creation succeeds
- On docker.go: adds a test on the presence the socat command which was
  failing silenty if not installed

- Code Review 1
  - Fixed typo on Expected
  - The UT now fails if the PortForwarder could not be created

- Code Review 2
  - Simplify socat error message
  - Changing t.Fatal to to.Error on unit tests

- Code Review 3
  - Removing useless uses cases in unit tests

- Code Review 4
  - Removing useless initiliasiation of PortForwarder
  - Changing error message

- Code Review 5
  - Simplifying TestCast struct
  - Adding addition test in one test case
  - Closing the listener

- Code Review 6
  - Improving unit test