XD-1519 Adds missing Job Registry schema files allowing to use GemfireXD and Derby-style databases as main Spring XD storage.

Added files is a copy of MySQL schema files. Works fine with GemfireXD 1.3.0.
#1184
XD-2172 Parameterize transaction isolation level used by Spring Batch JobRepository

Add custom BatchConfigurer to the batch/batch.xml file to make the JobRepositoryFactoryBean settings
available for configuration via server properties. The Spring XD specific BatchConfigurer is a modified copy
of the org.springframework.batch.core.configuration.annotation.DefaultBatchConfigurer