Make MdTag immutable
Merge pull request #45 from jey/immutable-mdtag

Make MdTag immutable
Reduce logging for the actual adamSave job

Conflicts:

	adam-core/src/main/scala/edu/berkeley/cs/amplab/adam/rdd/AdamRDDFunctions.scala
Merge pull request #46 from nealsid/parquet-logging

Reduce logging for the actual adamSave job