* adding local pagination to bucket list
When there are more than 5000 buckets, browser ui
becomes unresponsive since react needs to create
5000 elements which takes browser resources.
So we show only 100 buckets for the first time,
and load more buckets when the user is scrolling down.
* move inline styles to less file
This commit takes the existing remove bucket functionality written by
brendanashworth, integrates it to the current UI with a dropdown for
each bucket, and fixes small issues that were present, like the dropdown
not disappearing after the user clicks on 'Delete' for certain buckets.
This feature only deletes a bucket that is empty (that has no objects).
Fixes#4166
