Curated training indels from Mills et al: http://genome.cshlp.org/content/21/6/830.full From the Broad v2.8 resource bundle https://www.broadinstitute.org/gatk/guide/article.php?id=1213 lifted over to hg38 coordinates by Alison Meynert https://github.com/chapmanb/bcbio-nextgen/issues/817
