fix:Factors maintain weight <0 through removal
Merge remote-tracking branch 'upstream/master' into feature/js-refactor

merging Model changes
Tri-state category checkbox
cleanup
default weighted overlay opacity is now 0.6
starting map zoom +1
View Region button resets map zoom and center
leaflet legend synced with screen legend

adding/removing layer in one filters into another
blue-to-orange now default ramp
Transit Scenario now default
Merge pull request #19 from echeipesh/feature/js-refactor

Changes from PP review