Replace https://github.com/satori/go.uuid with maintained version at
https://github.com/gofrs/uuid
Since the new version uuid.NewV4 returns an error when failing to read
from the random source reader we use uuid.Must to panic on error since
it's considered an unrecoverable error.
In future, if needed, we could handle the error instead of panicking.
Handle the task dependencies conditions:
* on_success (default if no conditions are specified)
* on_failure
* on_skipped
Not the runservice won't stop run but continue executing tasks that depends on a
parent also if this is failed