Attempt to fix nightlies by moving to stable branch of zinc.

* Move  builds to stable branches
* Create  builds on master for integration checks.
Upgrade to latest dbuild.

* Upgrade to dbuild 0.6.5
* Adapt build files for new dbuild.
* Fix references in each file so that we can build sbt, and
  tags are correct.
* Change sbt-republish versions so all-nightly builds don't
  mention for-IDE, since we don't want them on unstable
  masters.
Outline what the different build files mean, and their purpose.

Review by @gkossakowski
Merge pull request #13 from typesafehub/wip/fix-nightleis

Fix current nightlies.