Make it easier to switch the maven groupId in different branches

Different branches of our code use different Maven groupId values for the modules. Simplify the task of this conversion by:

1) Avoiding hard-coding of the groupId anywhere where it is not required, using

${project.groupId}

instead. Goal is to limit declaration of the group id to the root pom and to the groupId child element in each pom's "parent" element. Changing the groupId then becomes a task analogous to changing the maven version.

2) Eliminating unnecessary groupId elements where a child pom redundantly declares the groupId inherited from its parent.

3) Separating groupId elements from version elements by making sure artifactId is in between (rather than before groupId as is currently done in some poms.) This will help avoid spurious conflicts between commits the update the groupId and those that update the version.