Remove broccoli-unwatched-tree dependency. (#1122)
Remove broccoli-unwatched-tree dependency. (#1122)

This package is unused in ember-cli-mirage (and it has been deprecated upstream).
mixonic/ember-cli-mirage,samselikoff/ember-cli-mirage,makepanic/ember-cli-mirage,makepanic/ember-cli-mirage,unchartedcode/ember-cli-mirage,unchartedcode/ember-cli-mirage,jherdman/ember-cli-mirage,mixonic/ember-cli-mirage,cibernox/ember-cli-mirage,jherdman/ember-cli-mirage,samselikoff/ember-cli-mirage,samselikoff/ember-cli-mirage,unchartedcode/ember-cli-mirage,jherdman/ember-cli-mirage,samselikoff/ember-cli-mirage,jherdman/ember-cli-mirage,unchartedcode/ember-cli-mirage,cibernox/ember-cli-mirage