Select transcript, click on exon -> exon is selected.

WA behavior is to keep the parent selected.

And refactor handleFeatureSelection.

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>
Put spinner against a backdrop.

* Remove spin.js - use font awesome's spinner.
* Use Bootstrap modal for backdrop.

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>