Fix newline in gitignore
Call included hook with parentAddon or app

See
https://github.com/stefanpenner/ember-cli/pull/2381#discussion_r19381207
for context. Converts the included hook to pass the parentAddon if
applicable, otherwise the app. Updated test coverage and related code
to use this new structure.

Addons no longer receive parentAddon via their constructor.
Include a comment about why we aren't asserting
Alphabetize dependencies and clean up whitespace