CORE-1760 Improved test infrastructure

Use LiquibaseCommand for SDK main commands as well
CORE-1815 Liquibase SDK command to easily watch database

Initial version. Needs code cleanup and documentation
CORE-1815 Liquibase SDK command to easily watch database

Code cleanup
CORE-1815 Liquibase SDK command to easily watch database

Ajax polling for changelog changes
CORE-1815 Liquibase SDK command to easily watch database

Final cleanup