SPDX IDs

Switched to SPDX IDs for OSI approved licenses. File names also changed where necessary, however kept them all lowercase, to minimize changes this round.
Fixed a few other related bugs (Eiffel license, I believe, was duplicate, the BSD case had to be split). Added newer approved OSI licenses (last year or so), and updated data and scripts for consistency.
Removed the older named files and records about them.

I think the remaining question is:
* should file names no longer be necessarily lowercase? Now it's a mix, though IMHO it's easy to work with, and I don't see a problem.

Notes:
* there are no tests. I think current tests are obsolete since the OKFN service changed to raw data mostly, no longer built (probably https://github.com/okfn/licenses/commit/6714595529ccfc79ce7af33caf2a16461b237d69). It's a bit difficult to figure out what exactly to test in raw data. :)
* CC licenses not changed. Not sure they have to, because the service doesn't seem to have different versions, nor localized. Would versions be useful?

Should fix issue #24, locally tested. If redirections are necessary, and on github.io I guess it's not possible, we could re-add files with older names...