Refactored metadata management
* Metadata belonging to different functionality areas (i.e. common, hiv) now in separate classes
* Moved constants into same file as installation
Merge branch 'master' of github.com:I-TECH/openmrs-module-kenyaemr

Conflicts:
	api/src/main/java/org/openmrs/module/kenyaemr/Metadata.java
	api/src/main/java/org/openmrs/module/kenyaemr/metadata/MchMetadataProvider.java
	api/src/test/java/org/openmrs/module/kenyaemr/metadata/MetadataPackagesTest.java