Revert "Upgrade tukaani-xz to 1.6"
Revert "Upgrade tukaani-xz to 1.6"

tukaani-xz is a transitive dependency of commons-compress, which
depends on version 1.4

Revert back to 1.4 to keep the correct dependency. Also add notes
in the WORKSPACE file to prevent mismatching upgrades in future.

This reverts commit 58d988b611ee8cc2451a809c7d2f12f753fa351f.

Change-Id: If7ddb7fd7ade511c85aa28235890cbeb065991f3

WANdisco/gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,WANdisco/gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,qtproject/qtqa-gerrit,qtproject/qtqa-gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit