Make some things more explicit.

Some people were not familiar to the Ant build process, or downloaded
compiler files that didn't have the Gson dependencies.  I hope this
helps them now.
Announce the plans for stable releases.
Merge pull request #28 from piojo/describe-stable

Announce the plans for stable releases.
Merge pull request #27 from piojo/json-docs

Improve the documentation of the migration to JSON