Replaces paging toolbar and button images with high contrast versions
Merge pull request #896 from sonatype/7729_paging

Replaces paging toolbar and button images with high contrast versions
Drop service url accessor, not used
Make EventData and EventHeader Cloneable and Serializable.  Add copy() method to help create deep cloned copies.
Generate unique id for multifile zips and record id + part # in each header for future correlation
[NEXUS-7731] refactor event zip creation to use EventWriter vs. hard-coded File output.  Added initial impl that reproduces single-file behavior
Add helper to lookup a component in the global class loader context.
Use helper in sysinfo report generation and analytics event header factory.
Merge remote-tracking branch 'origin/master' into NEXUS-7292-scheduler-rework