Relax memory constraint on CI native stress test to 140M

`time -v` on my machine reports ~137M of total heap usage, with a
maximum GC heap size of 128M. I think this is enough, as we are not
yet looking at optimizing Gears for memory.

Nevertheless it is good to keep an eye on it.

Add developers to build.sbt

Move publish settings upwards

Set up `sbt-ci-release` (#72)

Commits to branch `release`, alongside with any tags, will trigger a release.

Merge pull request #25 from natsukagami/transform-values-with

Rename source.map => transformValuesWith and add warning