Small fixes for running Hadoop OutputFormats with HadoopCompat layer

This PR includes some fixes necessary to run a large Hadoop OutputFormat such as the HCatOutputFormat on HDFS. Since HCatOutputFormat uses a custom output file name the following exception is thrown which is now fixed:

```java
eu.stratosphere.client.program.ProgramInvocationException: The program execution failed: java.lang.IllegalArgumentException: This method can only be called from within a Job
	at org.apache.hadoop.mapred.FileOutputFormat.getUniqueName(FileOutputFormat.java:286)
	at org.apache.hive.hcatalog.mapreduce.FileOutputFormatContainer.getRecordWriter(FileOutputFormatContainer.java:107)
	at org.apache.hive.hcatalog.mapreduce.HCatOutputFormat.getRecordWriter(HCatOutputFormat.java:246)
	at eu.stratosphere.hadoopcompatibility.mapreduce.HadoopOutputFormat.open(HadoopOutputFormat.java:122)
```

Furthermore there were some issues with HDFS that were also fixed with this PR.