Travis add mpl backend setup

[bsipocz]

This is to address and close #26.

@astrofrog - do we need to test this somehow?

[astrofrog]

Of course, we could also simply always run those commands - I'm not sure if there would be any downsides?

[astrofrog]

@bsipocz - I think we should actually just always run these commands, BUT we need to check that the OS is linux.

[bsipocz]

@astrofrog - Rebased and removed the env variable so it's always set.
As it's only included in setup_conda_linux.sh, the OS should be linux.

[bsipocz]

Rebased again. And I've also sent a feature request to support@github whether they would consider adding a "Rebase branch" button next to the current "Update branch". Latter merges master back to the given feature branch which we don't like that much.

[bsipocz]

@astrofrog - Do you know how to disable the coveralls here, so it can't screw up the statuses? It doesn't make much sense anyway as the only python here is the test itself, and we only run it to make sure we installed all its dependencies.

[astrofrog]

@bsipocz - I've disabled the coverage status (it's an option on coveralls.io)

[bsipocz]

Thanks.

[bsipocz]

Rebased on #45 so a new build is triggered (and that one should go in asap as it already causes trouble that the package names are not always lowercase (eg Cython))

[astrofrog]

@bsipocz - it looks like this will need rebasing

[bsipocz]

I'll rebase once we merge #51 (as a rebase is needed after every merge).

[astrofrog]

@bsipocz - sounds good!

[bsipocz]

Rebased

[bsipocz]

Merged this to avoid YAR (yet another rebase) ;)

[astrofrog]

Thanks! I just discovered that packages will need to remove these lines otherwise the Travis build fails. I'll email the mailing list for affiliated package maintainers.

[bsipocz]

Ouch. Should we set this with an env variable then?

[bsipocz]

Also some packages are checking for qt, while others seems to be ok with pyside. Should be put that here, too?

[astrofrog]

@bsipocz - ok, maybe it makes sense to add an environment variable XVFB for people to opt in. Could you do that? I wouldn't touch the QT_API variable which some packages set though, that's more specialized (is that what you meant?)

[bsipocz]

Yes, I'm doing it now. And yes, that's what I meant, that we cannot do it being generic enough anyway to make all the affiliated packages happy.