better support for solvebio as an optional dependency; add docs to README (cbmi/varify#200); conditionally add solvebio module to INSTALLED_APPS; only attempt to import solvebio module once in variant resources.py; fix bug in condensed result view templates.js in case where solvebio clinvar query fails

Signed-off-by: David Caplan <dcaplan@gmail.com>
Merge pull request #207 from solvebio/solvebio-docs

Add docs about SolveBio to README and better treat SolveBio as an optional dependency