XD-2430 Adding a Sqoop tasklet and Sqoop batch job
XD-2484 Update spring-data-hadoop version to 2.1.0.M3
XD-2483 Add codec option to hdfs-dataset sink
XD-2409 Changing correlation-strategy-expression

- partial reversal of earlier change to avoid errors when payload is a String
XD-2521: Configure Compression Level

Allow the compression level to be set in application/servers.yml.
XD-2079: Add Retry to the RabbitMQ Source

JIRA: https://jira.spring.io/browse/XD-2079

Add StatelessRetryOperationsInterceptorFactoryBean to RabbitMQ source

Tested with the following and `LocalMessageBus` so the transformer exception is thrown to the source:

`xd:>stream create foo --definition "rabbit --enableRetry=true | transform --expression=payload/0 | null" --deploy`
XD-2533 Upgrade to Reactor 2.0 M2
XD-2432, XD-2433, XD-2465, XD-2466, XD-2467: wip
Fixes and polishing

 - Reduce the number of jars for spark application
 - Fix message bus dependnency
 - Plugins to use a different approach to check for spark module
 - Fix jetty server dependencies
Container criteria: PoC
Introduce Spark ModuleType
Fix compilation errors and other issues