sacCer2 to sacCer3
Move INDEX_FNs so outside packages can get a list of supported indexes.
updated yaml; sacCer2 => sacCer3
Remove automatic uploading to S3.
Merge pull request #169 from kern3020/master

updating sacCer2 to sacCer3
Include download of human ancestral sequence used by VEP LOFTEE plugin to assess loss of function mutations
Basic support for Arch linux detection: no package management but minimal detection to enable custom and other package installation. Fixes chapmanb/bcbio-nextgen#449
Turn on ancestral fasta human downloads by default