Fix quaff for elixir 0.14.x
update travis matrix to correlate erlang 17 with elixir >= 13
Merge branch 'mweibel-fix-for-elixir-14'
fix some issues with merged PR; get tests working on 0.13.3
.travis.yml builds only with 0.13.3
switch to Exunit 'on_exit' callback
.travis.yml build with 0.14.3 and stable
use patched rebar-elixir-plugin