Add npm module skeleton; load plugin translations

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Move Angular app plugin code under frontend/app

Analog to core commit:
https://github.com/opf/openproject/commit/6ec5ca58edc6d8dbf0efd14aab189dead0da6fa2

Signed-off-by: Alex Coles <alex@alexbcoles.com>
No longer load Angular code via asset pipeline

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Merge pull request #115 from finnlabs/feature/webpack-i18n-support

Fix loading of I18n in plugins from Angular application; Reorganise frontend code