Revert "Comment out The Filtering is not fully implemented"

This reverts commit dd780e7d7982783fef22a8ad22326758e025deab.
Upgrade projects to Java7 Bundle-RequiredExecutionEnvironment:
Whitespace changes
Nexus Filters and dependent implementation and test

Includes new dependency on org.apache.commons.lang.builder to be able to
use EqualsBuilder and HashcodeBuilder
Merge branch 'nexus_navigator_sorters_and_filters'
Add tests for toString and hashCode