Installation fixes: bump pysam and cyvcf requirements. Ensure gemini configuration is written even if all downloads fail to allow clean updates via 'gemini update'
Merge pull request #163 from chapmanb/master

Installation fixes: bump pysam and cyvcf versions and allow 'gemini update' even if initial installer fails on installing data
Bump version of cyvcf to fix installation issues from missing files in 0.1.6
Merge pull request #164 from chapmanb/master

Bumps cyvcf versions to include fixed installation version from pypi