[El] epsg file missing and proj is looking for it

[Mathieu Baudier]

> There have been concerns from some packagers about whether the epsg
> init file is really free.  I don't recall what the rationale was for
> considering it non-free but the EPSG folks do ask that you don't modify
> the data and still represent it as coming from them.

Ok, so adding proj-epsg as a dependency to proj should do the trick.
We can put this in testing quite soon.