glob list instead of simple hdfs list and pattern support for input

[angadsingh]

Right now hraven accepts a simple hdfs path as input folder and will fetch all job history + conf files underneath it. This pull request adds support for specifying a pattern with wildcards (*) and using hdfs api's globStatus method to list files instead of hraven's recursive listFiles method. This way one can easily shard hraven's job to different years/months/days.

[jrottinghuis]

Interesting idea. Doesn't the RM already do this (sharding history files by date) ? For Hadoop 1 we had the original directory all in one place (where the history server can read from), then we separately ran JobFilePartitioner to shard the files into a yyyy/mm/dd directory structure. Are you doing a different setup ? Can you explain how your history files appear in one place and then get shared, or how that works for you ?

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