Tests: Fix more bad assumptions about routing in TransportTwoNodesSearchTests.
Revert "Tests: Temporarily ignore RoutingBackwardCompatibilityUponUpgradeTests."

This reverts commit 181bd6e56a2e6cfa1e0e85a5a7778cae5a8e62e1.
Test: make field `id` is defined in mapping, so sort can't fail
Merge branch 'master' into enhancement/lucene_5_0_upgrade