taskrunner could pass cli flags & args down to tasks

[EmmaOnThursday]

It would be nifty if Taskrunner could accept flags for its tasks, and pass them down.

If it's easier as an MVP, this could work only if a user requests a single task (probably requires less warning of users about potential side effects), but there are also flags that might be helpful across lists of tasks, like --dryrun maybe ? or --describe ?

[kencheeto]

@toniihsia is this closed by #48 ?