[ADAM-423] Sanitize Avro strings when converting back to SAM.
[ADAM-424] Fix attempts to realign indels when there is no consensus.
[ADAM-425] Skip realignment if no targets are found.
[ADAM-426] Add ability to override indel realigner defaults.
Merge pull request #427 from fnothaft/indel-realigner-errors

Fixes for indel realigner issues