Workflow::find_cnodes not working with `cron`

[jfrioux]

When testing cron

sequence 
   cron '*/5 * * * *'
    bob _

Receiving an error in app/models/floristry/workflow.rb:202:in find_cnodes`

Execution is started with no errors in Flack.

Needs further investigation.

[jfrioux]

Documenting progress.

Brought some changes on my fork that handle the partial(s) rendering.

Thought, it seems that we made some assumptions around the cron|schedule|every that don't hold:
1st - Can't be encapsulated in a sequence, as it seems to expect it will be the top unit. Having a sequence with a nested cron will terminate and the cron won't behave as we'd expect.
2nd - That being out of the way, nids in a cron don't follow the same pattern, as each runs stays attached to the same node. For example, I launched a task with a cron that runs at every minute, here's how nids look like (at Trail.insert_in_tree(tree, nid, payload):

["0", "1", "1-90"]