Ensure we do not add `ember-addon` twice.
Merge pull request #1982 from rwjblue/do-not-add-ember-addon-twice

Ensure we do not add `ember-addon` twice.
Merge compiled addon/templates into addon/ JS tree.

This allows addon/templates to be properly available inside the
my-addon-name.js file with the correct module name.
Add addon template precomilation smoke test.