Remove unused addon folder to avoid cli deprecation warning

[jheth]

On app startup this deprecation warning prints to the screen:

DEPRECATION: Addon files were detected in /Users/test/.../node_modules/ember-cli-stripejs/addon, but no JavaScript preprocessors were found for ember-cli-stripejs. Please make sure to add a preprocessor (most likely ember-cli-babel) to in dependencies (NOT devDependencies) in ember-cli-stripejs's package.json.

[jheth]

@kellysutton What do you think of this change?

[kiwiupover]

@jheth I think we should fork for now.

[mufid]

Any working fork for this?