Population Widget and Tooltip Edits

Cici Punch List (#16)

* PopulationOnlyWidget. It begins

* Population Only Widget build out

* WidgetService. Remove non-existent css class

* Bug fix: context-menu dismissal nolonger disables tooltips

* Add Assemblies to context menu. It begins

* Assembly context menu build out

* Prep for AssemblyVisualizationLook tooltip edit

* PopulationWidget. Remove thin dividing line between items

* PopulationWidget and Tooltip edits

* clean up

* typo

* Context Menu hacking

* Population tooltip. Now highligts selected population

* Added population count to tooltip

* Population Tooltip futzing

* Added release tag retrieval function

* Added Info button