change package name to smart.who.int.immunization-measles

[costateixeira]

The canonical URL http://smart.who.int/smart-immunizations-measles can be simplified - http://smart.who.int/immunizations-measles

This would require the package id (who.fhir.smart-immunizations-measles) to change as well.

Proposed name is smart.who.int.immunization-measles