Merge topic 'update_version_to_4.2.0-RC1'

3f54af14 Update version to 4.2.0-RC1
Move VTK forward to bring in pvweb fix supporting Python 2.6

Change-Id: Ib91c2816aa197bdd4689640ea6e697744bf985af
Merge topic 'bring-vktweb-fix-for-python26' into next

13c04c98 Move VTK forward to bring in pvweb fix supporting Python 2.6
12afe9f4 Merge topic 'update_version_to_4.2.0-RC1'