add a `strict` mode to readMetadata()
add a `strict` mode to readMetadata()

Test cases will set this to `false`, because they're
missing `scripts.start` and other required properties in this function

zeit/now-cli,mike-engel/now-cli,zeit/now-cli,zeit/now-cli,zeit/now-cli,southpolesteve/now-cli,southpolesteve/now-cli,zeit/now-cli,zeit/now-cli,zeit/now-cli