Create Liquibase snapshot files for openmrs-core 2.4.x

Each time a new branch is created for a minor version of openmrs-core new Liquibase change log files need be be added to the openmrs-core master branch.

With the creation of the 2.4.x branch the following change log files need to be created and added to the master branch:

• api/src/main/resources/org/openmrs/liquibase/snapshots/core-data/liquibase-core-data-2.4.x.xml
• api/src/main/resources/org/openmrs/liquibase/snapshots/schema-only/liquibase-schema-only-2.4.x.xml
• api/src/main/resources/org/openmrs/liquibase/updates/liquibase-update-to-latest-2.5.x.xml

The file liquibase/README.md describes how to create and test these change log files.