rename getMetadata() to readMetaData()
rename getMetadata() to readMetaData()

Matches what it's called elsewhere in the codebase

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