Revert "docs(readme): add Greenkeeper badge"
Revert "docs(readme): add Greenkeeper badge"

This reverts commit 1e136e2cf8153b347af660e0cc484897b778d7aa.

liqd/a4-meinberlin,liqd/a4-meinberlin,liqd/a4-meinberlin,liqd/a4-meinberlin