XD-1461 Use Hadoop mini-cluster test support in XD tests

- Remove HadoopFileSystemTestSupport
- Change RemoteFileToHadoopTaskletTests, RemoteFileToHadoopTests and
  JobCommandWithHadoopTests to use minicluster.

NOTE: I have serious trouble of running JobCommandWithHadoopTests during a normal build cycle. Only way I can run it is without clean task as you can see below:
```
./gradlew clean :spring-xd-extension-batch:build -x javadoc -Dtest.single=RemoteFileToHadoopTests
./gradlew clean :spring-xd-extension-batch:build -x javadoc -Dtest.single=RemoteFileToHadoopTaskletTests

./gradlew clean :spring-xd-shell:build -Dtest.single=JobCommandWithHadoopTests

org.springframework.xd.shell.command.JobCommandWithHadoopTests > testLaunchFtpHadoopJob FAILED
    java.lang.AssertionError at JobCommandWithHadoopTests.java:73

14:33 $ find . |grep spring-xd-extension-batch|grep jar


14:35 $ find . |grep spring-xd-extension-batch|grep jar
./modules/job/ftphdfs/lib/spring-xd-extension-batch-1.1.0.BUILD-SNAPSHOT.jar
./modules/job/timestampfile/lib/spring-xd-extension-batch-1.1.0.BUILD-SNAPSHOT.jar
./extensions/spring-xd-extension-batch/build/tmp/jar
./extensions/spring-xd-extension-batch/build/tmp/jar/MANIFEST.MF
./extensions/spring-xd-extension-batch/build/libs/spring-xd-extension-batch-1.1.0.BUILD-SNAPSHOT.jar


./gradlew :spring-xd-shell:test -Dtest.single=JobCommandWithHadoopTests
```

Internal error during the autowiring is:
```
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'ls.gateway': Unsatisfied dependency expressed through constructor argument with index 0 of type [java.lang.Class]: Could not convert constructor argument value of type [java.lang.String] to required type [java.lang.Class]: Failed to convert value of type 'java.lang.String' to required type 'java.lang.Class'; nested exception is java.lang.IllegalArgumentException: Cannot find class [org.springframework.batch.integration.x.RemoteFilePartitioner$Gateway]
```