Change openjpa-integration module pom's to reflect proper artifact-id

Minor updates to the openjpa-integration pom files to contain the proper artifact-id. This will help with the automatic creation of projects via the m2 (maven2) eclipse plugin. Discussed on Dev forum [1]... This change is in preparation for another integration set of tests for the L2 cache.

[1] http://n2.nabble.com/openjpa-integration-td3365002.html#a3365002