Give some indication that progress is happening

[tfausak]

When Purple Yolk is rebuilding your project, it's not possible to tell if it's actually doing anything. It needs some type of indication when:

• A rebuild has started (that is, :reload has been sent to GHCi).
• A rebuild is ongoing.
• A rebuild has finished, either successfully or not.

Often I will keep the "output" tab open just to see all this going on.