message: [java gradle] Update README to use a pom
  [skip ci]
diff: To build with a development version of this plugin, enter the directory
  containing this README and repeat as follows:
  -* make changes
  -* gradle build
  -* mvn install:install-file -Dfile=build/libs/bond-gradle-1.0.jar -DgroupId=org.bondlib -DartifactId=gradle -Dversion=1.0 -Dpackaging=jar
  +
  +* write some code
  +* `gradle build install`
  +* `mvn install:install-file -Dfile=build/libs/bond-gradle-1.0.jar -DpomFile=build/poms/pom-default.xml`
  +
  This will install the plugin to your local maven repository, which the other
  Java projects' build.gradles will use in preference to maven central.
  