Online builder - optimisations

[Reinmar]

CKEditor 4's dev builder needs ~1 minute and that's obviously too long for an online builder. Therefore the current online builder uses some optimisations in order to save the environment.

There are two unfortunate facts related to that:

• The online builder is not the same as the dev builder. It means that we have to maintain two builders what's costly and blocked improving them with time.
• Some optimisations that the online builder uses might have blocked some improvements - for instance - creating source maps.

We need to decide how we are going to solve online building in CKE5, because it will affect the architecture or the architecture will affect online building.

Questions, mostly to @wwalc:

1. Could we use exactly the same builder, with no additional optimisations? How many unique (not yet cached) packages are created every day?
2. What optimisations are we using now?

[Reinmar]

I guess that the architecture and the tools we chose make it pretty clear that we won't have an online builder.