Fix release.py write-announcement to be aware of the anchor.

I've made a long string of releases with the wrong anchor for 1.7.x.
This isn't perfect since we have to remember to bump the version before
using the tool when making a new minor, but it help reduce the problem.

* tools/dist/release.py
  (recommended_release): New variable to keep track of our recommended line.
  (write_announcement): Set the tags based on the version number and avoid
    calculating the major/minor string twice.

* tools/dist/templates/rc-release-ann.ezt
  tools/dist/templates/stable-release-ann.ezt: Use anchor data instead of hard
    coded anchor values.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1595936 13f79535-47bb-0310-9956-ffa450edef68