Remove unused dependency (#1136)
Remove unused dependency (#1136)

This is now unnecessary thanks to this PR:
https://github.com/brandonjmckay/ember-prism/pull/20
travis-ci/travis-web,travis-ci/travis-web,fotinakis/travis-web,travis-ci/travis-web,fotinakis/travis-web,fotinakis/travis-web,travis-ci/travis-web,fotinakis/travis-web