Cleared relative path to bom module parent pom

Before this fix Maven builds would report a warning on inconsistency between actual parent pom and pom at parent relative path for Jersey BOM module (Maven default parent.relativePath is ../pom.xml) .

This patch fixes the issue by clearing the parent.realtivePath property.

Issue: JERSEY-2686
Merge pull request #116 from sslavic/patch-2

Cleared relative path to bom module parent pom