Navigator model filters out fields with empty values

In some situations, the implementers need to be able to parse and conditionally display the values of a form. For example, in this TB screening form, the user would like to be able to indicate in the confirmation screen which of the questions was answered:

https://github.com/PIH/openmrs-module-pihcore/blob/master/omod/src/main/webapp/resources/htmlforms/sierra_leone/vitals.xml#L838

Currently, the NavigatorModel filters out fields with empty values:

https://github.com/openmrs/openmrs-module-uicommons/blob/master/omod/src/main/webapp/resources/scripts/navigator/navigatorModels.js#L346

I suggest we expose to the display-template a new variable, values that includes all fields values, including the empty values.