FakeFamily improvements

[piotrszul]

Some ideas on how to improve fake family generation:

• Add reading all files from HDFS (including ped and spec)
• Review and improve hail support for phased genotypes
• Added one pass generation of independent mutations( generate mutation for all individuals in one pass and distribute them per individual)
• Scala/Python API for fake family generation
• Performance improvements for offspring genotype generation (use indexed sequence rather than HashMap)
• Add mutations based on fasta (actual sequence file)