Extend from InvisibleAction for conciseness
Use the timestamp of the build.

When used in matrix project, this ensures that all configuration builds check out the consistent state.
CVS plugin was originally written to behave that way, but it appears that the behaviour was lost in
36491459134c5858ea50ae460ca412d7a62b78f1 refactoring.
Wrote a tl;dr version at the top
Doc improvement