Lock yarn dependency, fix chrome dependency, upgrade node

This creates a new image which:

• upgrades node from v7.x to v8.x
• upgrades yarn to v1.0.2 and locks it at that version
• upgrades chrome to v61 (fixing broken master)

It also works around broken Chrome version images by commenting out build images which can no longer be built due to yanked PPA versions. Adds documentation for working with older versions of Chrome when images need to be recompiled.

closes #14 (closed)

changed title from Add Chrome 61 to build images to Lock yarn dependency, fix chrome dependency, upgrade node

changed the description

merged

thanks @stanhu

mentioned in merge request !55 (closed)

mentioned in issue #13