Introduce preSetup and preTeardown callbacks
Introduce preSetup and preTeardown callbacks

Necessary to assign callbacks that are performed before any others,
such as those that modify the resolver.
chadhietala/ember-test-helpers,martndemus/ember-test-helpers,seanpdoyle/ember-test-helpers,winding-lines/ember-test-helpers,HeroicEric/ember-test-helpers,ef4/ember-test-helpers,bcardarella/ember-test-helpers,switchfly/ember-test-helpers,OrKoN/ember-test-helpers,blimmer/ember-test-helpers,tsing80/ember-test-helpers,HeroicEric/ember-test-helpers,blimmer/ember-test-helpers,winding-lines/ember-test-helpers,seanpdoyle/ember-test-helpers,tsing80/ember-test-helpers,ef4/ember-test-helpers,switchfly/ember-test-helpers,OrKoN/ember-test-helpers,martndemus/ember-test-helpers