change step state_strings to state_string: DB model
change step state_strings to state_string: DB API
change step state_strings to state_string: data API + consumers
remove outdated TODO
change build state_strings to state_string: DB model
change build state_strings to state_string: DB API
change build state_strings to state_string: Data API + consumers
update docs to specify right type for state_string
Merge pull request #1269 from djmitche/bug2818b

Change state_strings to state_string

See ticket:2818