Update how Supervisor initiates children

[rogalskib]

Update how Supervisor initiates children as per https://hexdocs.pm/elixir/Supervisor.html

[danhper]

Hi and thanks for the PR. Could you also please update the travis build to remove 1.4? Thanks!

[rogalskib]

Glad to contribute. Busy at work now, but will update the travis build in the next couple of days.

[woojiahao]

Hi @rogalskib , are you still planning on working on this issue? I can help with making a new pull request to modify the Travis build. Thanks!

[rogalskib]

@woojiahao, yes, should have time this weekend.

[barseven]

@woojiahao travis build was updated, here is a pull request from my other account https://github.com/HashNuke/hound/pull/253