fixed caching_mode='unlimited' - #778

@hejung @dwhswenson I think this can be merged. Obvious typo. Thanks for fixing it.

Please note that we have changed to the OPS license from LGPL (2.1 or later) to MIT. For any pull request to OPS that was started while the license was still LGPL, I need an explicit confirmation that you approve of the license change. Please add a comment with something like "The changes in this pull request are licensed under the MIT license."

The changes in this pull request are licensed under the MIT license.

@hejung : Could you do a rebase or merge our current master into this branch? I tried to re-run the CI just to be sure that it still worked (I mean, there's no way this would break anything, but always be safe). It appears re-running the build uses the .travis.yml from the original build. Our .travis.yml has changed since then, and the repo isn't compatible with the old Travis script. Thanks!

Done. Sorry for the delay.

Thanks! Merging this.