dropdown and tooltip adjustments
PORTAL-897 - Fixed dynamic positioning based on viewport top and bottom edges.
Fixed a bug where a checkmark could be shown multiple times on the checkbox and the radiobutton widgets.
adding Back-to-Top component
Merge pull request #29 from davidamador/mods

Dropdown modifications (merge)
merging non-modal-dialog-positionning
Merge pull request #31 from davidamador/btt

adding Back-to-Top component (merge)
updating README and build script for v2.4 release
updating comments for shared-ui deploy in tm360
targeting CSS overrides to checkbox and radio controls for .tm360 container; fix requirejs config paths