Allow actions to return more meta data about the status than pass/fail

[abh]

It'd be nice if an action could return more meta-data about a status than just pass/fail. For HTTP the response time thing is useful enough, but other checks might want to return a different value. As an example the MySQL check could return how many rows in a table; a disk-free check how much disk space is left (in addition to "there's enough, all ok").

[jeffsu]

Thanks for the feedback. I'll look into adding some of the features soon.