[Tests] Move to Ubuntu 14.04 on Travis CI

[PeterDaveHello]

Since Ubuntu 12.04 is pretty old now, it's also going to EOL next month,
maybe we can just move on Ubuntu 14.04 first.

[PeterDaveHello]

The first build failed since log is too long, the second build failed since the npm detection bug and will be fixed in #1334

[ljharb]

I'm confused; the x is there intentionally so the failure messages will be more useful, and I want to keep it.

You're saying that #1334 works on Ubuntu 12 but breaks on Ubuntu 14?

[PeterDaveHello]

The logs are too many that the test will be killed as you can see in the raw logs, and yes, #1334 is broken on Ubuntu 14.04, and it's just because its logic is just wrong, as you can see here:

Ubuntu 14.04:
https://travis-ci.org/PeterDaveHelloKitchen/nvm/builds/215792358

Ubuntu 12.04:
https://travis-ci.org/PeterDaveHelloKitchen/nvm/builds/215792662

Not sure why nvm is already enabled even we do nothing in Ubuntu 12.04 on Travis CI

[ljharb]

Why are the logs too large for ubuntu 14, but not for ubuntu 12?

[PeterDaveHello]

Actually I am not very sure about this part yet, but IMO the log is truly too long, maybe we shouldn't write everything to the standard output, maybe just file, or just to enable the -x manually if test failed, otherwise, the overhead to the CI is too huge.

[ljharb]

k, #1334 is closed; let's try rebasing this on top of that.

I'm still not convinced about removing -x; i went to a lot of trouble to add it and I don't understand why travis log lengths would need to be different on different ubuntu versions.

[PeterDaveHello]

Another point I can't understand ... it just passed the tests without removing -x, so maybe we can just leave it alone now.

[PeterDaveHello]

Anything else I can do?

[PeterDaveHello]

Maybe the too long log failed it's caused by the failed test, which prints long log?

[ljharb]

Does using trusty enable us to drop some of the addons?

[PeterDaveHello]

Don't think so, but it's good to migrate to the newer environment (though actually 14.04 is not new at all 😅 )