Dash-html-components

Added
- Added `data-dash-is-loading` attribute to all components, that holds the new `loading_state.is_loading` prop.

Changed
- Added `.idea`, `tests`, `dist`, `.circleci` to npmignore.
- Added repository url and long_description to setup.py
- Merged in `dashHtmlComponents` R package and updated to 0.13.5

Removed
- Removed click events - these have been obsolete since 0.7.0 [89](https://github.com/plotly/dash-html-components/pull/89)

Fixed
- Fix build from wrong dash version.

Fixed
- `n_clicks`/`n_clicks_timestamp` PropType changed from invalid `integer` to `number`.
- omit `n_clicks`/`n_clicks_timestamp` from wrapped element props.

Fixed
- Fixes Python3.7 incompatibility with `0.13.0` and `0.13.1`.

Changed
- Regenerated classes with Python3.7 to remove `async` keyword.

Fixed
- Renamed `__init__.py` external_path to dash_html_components.min.js