Update import paths after move from tools repo

Also:
- Move the watcher to cmd/watcher (somehow this was missed earlier).
- Move dashboard package from the repo root to its own directory.
- Update docker build scripts. (Although not yet the version hashes in
  the Dockerfiles; this leaves the docker builds broken, but they were
  already broken after moving the builder to cmd/builder. They'll be
  fixed in a followup CL after this one is submitted.)

Change-Id: I29a9758da1f3c60446e3ce18174c0df26e4d8325
Reviewed-on: https://go-review.googlesource.com/3077
Reviewed-by: Andrew Gerrand <adg@golang.org>
21 files changed