Use packs rather than readymades

[psychemedia]

Via Mark Hall:

Regarding the readymades, I would suggest just making them packs. While a pack obviously requires a package, the setup otherwise is very light-weight and then you are not re-implementing something that is already there.

The name of the entry-point is ou_container_builder

All the current packs use the entry-point structure. The only difference is that the code is installed via the default ou-container-builder package. Apart from that the loading process for them uses the entry-points (so that in the future I can easily factor them out, if necessary)