fix pom.xml files in JBT and JBDS repo such that only component root poms reference parent pom (all others just look up to .. for parent)

Currently, there are many plugin pom.xml files which reference the parent pom directly. This is bad.

Instead, only ~/trunk/<component>/pom.xml should reference the parent pom, which can then be pulled from nexus:

Downloading: http://repository.jboss.org/nexus/content/groups/public/org/jboss/tools/org.jboss.tools.target.platform/0.0.1-SNAPSHOT/maven-metadata.xml
Downloaded: http://repository.jboss.org/nexus/content/groups/public/org/jboss/tools/org.jboss.tools.target.platform/0.0.1-SNAPSHOT/maven-metadata.xml (383 B at 0.2 KB/sec)
Downloading: http://repository.jboss.org/nexus/content/groups/public/org/jboss/tools/org.jboss.tools.target.platform/0.0.1-SNAPSHOT/org.jboss.tools.target.platform-0.0.1-20110304.023858-41-unified.target
Downloaded: http://repository.jboss.org/nexus/content/groups/public/org/jboss/tools/org.jboss.tools.target.platform/0.0.1-SNAPSHOT/org.jboss.tools.target.platform-0.0.1-20110304.023858-41-unified.target (20 KB at 21.5 KB/sec)