disable the edit link in docs

unify contribution guides

Closes #253

replace index.md link

add support for travis CI

Clean up FVA

Clean up tests

(saves time)

It's a bit confusing anyway for this use-case (if you're reading the
documentation you usually don't want to edit it).

Side effect:
Closes #245

fix banner on 80col terminal

fix a problem in screening

How come this didn't break with single-worker tests?

This Is Important Commit And Must Be Merged With Highest Priority

increase coverage of serialization + fixes

add the abstract screening helper + on-disk externalized models