Get read input from adam records

Closes #246 and #80

This is somewhat under-tested since it should be easy to direct comparison between the reads read in both methods, but this fails due to one field.  If inferredInsertSize is None then all of the tests pass.
I think file naming conventions are less established for ADAM than for bam. Might want to change this check to test for ".bam" instead of ".adam". Going further, maybe consider requiring the file to end in either ".bam" or ".adam" and failing otherwise. As it is now if someone names their file "test.parquet", they will get a confusing samtools / hadoop bam error, instead of something like "we don't know what that file extension means."