Events are broken; base_component.parse_events needs updating #232

Moving from dash-html-components==0.9.0rc1 to dash-html-components==0.9.0 causes any callbacks using click Events to break as Dash._validate_callback now raises a NonExistantEventException. This appears to be because base components are now generated with available_events = []. This is due to base_component.parse_events not being updated to handle the new PropType data structure used to define Component props created by dash_html_components and dash_core_components.

This is also causing the tests to fail now, as invocation of a callback with a valid event in test_exception_event_not_in_component is now failing. So would be good to prioritise this.