[SERVDEV-49] - Added first version for multi select drop down to be used as filter selector
[SERVDEV-49] - Updated Multiselect Dropdown directive
- Multiselect directive now can:
-- Receive a parameter "selected" which will be updated with the selected values
-- Receive a parameter "options" that identifies the list of possible selectable options
-- Receive a parameter "groupBy" that identifies the option property that groups the options
-- Receive a parameter "display" that identifies the option property which value will be displayed in the drop down
-- Receive a parameter "select" that identifies the option property which value will be selected