Travis CI: Explain why we use "cpp" instead of "python"

[sschuberth]

Because that deserves some explanation.

[pombredanne]

@sschuberth I reckon it looks odd. But this is NOT a bug. We have to use the cpp config because we are using the multi-os (linux + mac) travis support (which is enabled only by special request) per https://github.com/nexB/license-expression/blob/025fee38d84aa19f32050c0802eb27e0f0852bc7/.travis.yml#L3 and this has to be used then. So if you do not do that, whatever the internal reasons may be at Travis the mac build will not work at all .... which is what you see just here in the build results

[sschuberth]

@pombredanne I was assuming something like that after seeing the OSX builds fail. I'll change this PR to add a comment to .travis.yml instead.

[sschuberth]

@pombredanne Does the wording of the comment nail it?

[pombredanne]

I guess you meant deliberately?

[sschuberth]

Indeed. Thanks for fixing it already.

[pombredanne]

Thanks! I tried the "commit in your branch feature" and it works fine.