Overhaul TravisCI

[lukeyeager]

• Run on Ubuntu 14.04 (close Mark the expected TravisCI distro explicitly #3407)
• Test cuDNN builds (close Travis should check that USE_CUDNN builds #2492)
• Build with OpenBLAS
• Rewrite all scripts in scripts/travis/ for clarity and consistency

TODO:

• Don't install the full CUDA toolkit

wontfix:

• Python3 for raw Makefile build (ImportError: dynamic module does not define init function (PyInit__caffe) #2478)
• Cache protobuf3 build directory (because Migrate to new Travis-CI container infrastructure #3798 (comment))

[lukeyeager]

I was going to try to fix the Python3 + raw Makefile build, but I realized that we weren't testing it before. So I'll leave that for someone else to fix. But I'm skipping it more explicitly now.

[shelhamer]

For notes like this we like to use TODO(handle) like the TODO(shelhamer) you see in the Caffe code. XXX isn't currently used in the project for highlighting comments.

[lukeyeager]

Ok. Want me to assign it to anyone in particular?

[shelhamer]

Oh, I read this as the author of the TODO, and not the assignee, so TODO(lukeyeager) is fine. Don't worry, it's not a promise to do it yourself haha. Although versioning records the line author it's nice to have a quick reference for who thought of the TODO in case there are later questions or you want to search for commits by the same author for context.

[lukeyeager]

done

[lukeyeager]

I've removed the protobuf3 build cache:

1. The cuDNN build is the long pole anyway
2. Very few people would know what's going on if/when the cache gets screwed up, and it requires a @BVLC member to clear the cache. Not worth the trouble in my opinion.
3. We would need to decide a reasonable timeout limit greater than the default of 5 minutes if caching was going to be useful (see Migrate to new Travis-CI container infrastructure #3798 (comment)).

[lukeyeager]

I've done all I plan to do for this PR. Please let me know if other changes are necessary.

[flx42]

Nice, since you trimmed the CUDA dependencies, is it building faster now?

[lukeyeager]

Nice, since you trimmed the CUDA dependencies, is it building faster now?

The build didn't speed up, but installing dependencies doesn't take as long. As expected.

[shelhamer]

Thanks for the CI care @lukeyeager! These are welcome improvements.

[lukeyeager]

Sure thing. Can't wait to solve #3351 so we can cut the test matrix in half.