Output aligment stats in plain text format

[jtarraga]

Currently, the 'alginment stats' command line outputs stats in JSON format. In order to make more understable the stats, 'alignment stats' should output the stats in plain text format. A new optional parameter should be added, e.g.: --text:

./build/bin/hpg-bigdata-local.sh alignment stats --i test.bam.avro --text