CORE-1942 Support for changeSet "labels"

Added backwards compatibility methods as deprecated
Testing StatementLogicFactory, added explicit UnsupportedException
Merge branch 'master' into sql-execution-refactoring

Conflicts:
	liquibase-core/src/main/java/liquibase/RuntimeEnvironment.java
Cleaning up, documenting and testing Statement objects
Cleaning up, documenting and testing Statement objects