Append immediate execution to start action

This PR improves **Start** action for immediate execution and append **Schedule** action to avoid it.

Ref. threefunkymonkeys/crocodile#3
@emancu Excellent points.
I won't change the method name for now. It's seems like too much for just syntax sugar.
I'll consider a future method deprecation but I think the best is to revert this change since it was even out of the scope of this PR and we're unnecessarily delaying it.

> We can continue this discussion on IRC.

I really prefer keeping discussions in this context for the sake of documentation. Also, people who is interested but miss the IRC chat can be up to date as well.

@lguardiola could you please revert the method renaming, so we can move on here?

Thank you both for your collaboration!!