Fix configuration on hadoop mapreduce job

[gom]

I got following "Wrong FS" errors, when I run SegmentCreation job with pinot-hadoop.

It seems new Configuration() loads only empty core-site.xml file, and loads fs.defaultFS value as file:/// in the MR job.
It will be fixed using context.getProperty() in the job.
Mapper would be better to use JobConf from their context.

Similar issue as #63.

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Error on the map job log:

2017-01-17 09:39:50,712 ERROR [main] com.linkedin.pinot.hadoop.job.mapper.HadoopSegmentCreationMapReduceJob$HadoopSegmentCreationMapper: Got exceptions during creating segments!
java.lang.IllegalArgumentException: Wrong FS: hdfs://<HOSTNAME>:8020/user/pinot/input/data/part-4.avro, expected: file:///
	at org.apache.hadoop.fs.FileSystem.checkPath(FileSystem.java:661)
	at org.apache.hadoop.fs.RawLocalFileSystem.pathToFile(RawLocalFileSystem.java:87)
	at org.apache.hadoop.fs.RawLocalFileSystem.deprecatedGetFileStatus(RawLocalFileSystem.java:619)
	at org.apache.hadoop.fs.RawLocalFileSystem.getFileLinkStatusInternal(RawLocalFileSystem.java:850)
	at org.apache.hadoop.fs.RawLocalFileSystem.getFileStatus(RawLocalFileSystem.java:614)
	at org.apache.hadoop.fs.FilterFileSystem.getFileStatus(FilterFileSystem.java:422)
	at org.apache.hadoop.fs.FileUtil.copy(FileUtil.java:340)
	at org.apache.hadoop.fs.FileUtil.copy(FileUtil.java:292)
	at org.apache.hadoop.fs.LocalFileSystem.copyToLocalFile(LocalFileSystem.java:88)
	at org.apache.hadoop.fs.FileSystem.copyToLocalFile(FileSystem.java:1996)
	at com.linkedin.pinot.hadoop.job.mapper.HadoopSegmentCreationMapReduceJob$HadoopSegmentCreationMapper.createSegment(HadoopSegmentCreationMapReduceJob.java:154)
	at com.linkedin.pinot.hadoop.job.mapper.HadoopSegmentCreationMapReduceJob$HadoopSegmentCreationMapper.map(HadoopSegmentCreationMapReduceJob.java:134)
	at com.linkedin.pinot.hadoop.job.mapper.HadoopSegmentCreationMapReduceJob$HadoopSegmentCreationMapper.map(HadoopSegmentCreationMapReduceJob.java:44)
	at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:146)
	at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:787)
	at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
	at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
	at java.security.AccessController.doPrivileged(Native Method)
	at javax.security.auth.Subject.doAs(Subject.java:422)
	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1724)
	at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:162)

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[lionelfeng]

I met the same problem and it took me one day to direct me here to save my ass. This PR did fix my issue and please merge this PR asap since the new Configuration() is really confusing... Thanks.

[kishoreg]

@jenniferdai can you please take a look at this PR

[jenniferdai]

@gom thank you for fixing this!

[gom]

@jenniferdai thank you for merging :)