[bower] move widget-specific dependencies to corresponding widgets
[bower] add bower.json for each widget
[bower] new name for core bower dependencies
[gulp] delete bower.json in clean task
[gulp] rename task bower to bower-install
[gulp] watch task watches for bower-base.json and any bower.json of a widget
[gitignore] ignore generated bower.json
[gulp] add generate-bower-json task and call it before bower-install
[npm] add gulp-json-editor dependency
[gulp] run generate-bower-json before bower-install