Travis CI: expand to test and deploy for Linux and Mac

[japaric]

This one is more complex. I hope I got it right on the first try. crosses fingers

[japaric]

I hope this right, this is meant to:

• run on a single build job, and
• the npm install stylus nib is only needed for this deploy script

?

[japaric]

Argh, about the Travis errors. doctests are known to not work correctly when --target is used with cargo test. Let me think about how to workaround this problem.

[japaric]

Fixed the doc test problem, but we now have a legit failure. The notify crate can't be correctly compiled for i686-apple-darwin because its fsevent{,-sys} dependencies aren't compiled for that target (see 1, note that i686-apple-darwin is missing). I propose not targeting i686-apple-darwin until that is sorted out.

[japaric]

All Travis CI tests are green. @azerupi r?

[azerupi]

I propose not targeting i686-apple-darwin until that is sorted out.

I suppose that is acceptable, 32-bits Macs are quite old.. There shouldn't be too much of them (I think) 😋

I will merge when I get home

[azerupi]

Merged, I will push a new release to test it :)