XD-1431 Fix review comments

- Remove Datasource initializer references and use XdBatchDatabaseInitializer to
initialize batch schema along with registry schema
- Create spring-xd-batch sub project
  - Use this project to hold batch related schema and classes
  - Delete spring-xd-hsqldb-server and move the HSQLServerBean and HsqlServerApplication classes into this
  - Create HsqlDatasourceConfiguration which imports hsql-datasource
- Update hsqldb-server scripts
  - Remove XD_HOME and XD_CONFIG references and use xd.data.home to specify hsqldb data directory
- Remove the use of explicit jdbc datasource profiles
  - Delete DataSourceVerificationListener