Releasing

For contributors, the jruby-rack release process goes something like the following:

1. Ensure that release version is correct in pom.xml and mvn install runs clean.
2. Ensure generated changes to src/main/ruby/jruby/rack/version.rb are checked in.
3. Ensure History.txt is updated with latest release information.
4. Tag current release in git: git tag <version>.
5. Push commits and tag: git push origin master --tags
6. Build gem: rake clean gem
7. Push gem: gem push target/jruby-rack-*.gem
8. Release jar to maven repository: mvn -DupdateReleaseInfo=true deploy
9. Bump the version in pom.xml to next X.X.X.dev-SNAPSHOT version, (run mvn install) and commit the changes.