Updates:
* gulp to 4.0.2
* gulp-eslint to 6.0.0
* stylelint to 4.3.1
* bootstrap to 3.4.1
* chart.js to 2.8.0
* jquery to 3.4.1
* mapbox-gl to 1.3.1
* moment to 2.24.0
Removals:
* bootstrap-daterangepicker
* backbonejs(code parts that weren't removed)
* d3
* underscore
Signed-off-by: Alfredos-Panagiotis Damkalis <fredy@fredy.gr>