Introduce v2 of entropy standard

[mbuechse]

v1 says that rngd must be installed, but that is not sufficient. It must be installed and running. Therefore create v2.

[mbuechse]

We will have to see whether the test script also needs to be changed. If #668 comes to pass quickly enough, then the script won't need to be touched (other than what is done in #668 itself)

addendum since this topic isn't time critical, let's wait for #668 (except we need to finalize SCS-compatible IaaS v5 earlier).

[mbuechse]

@artificial-intelligence I have to ask again: Do we really need this?

Con:

• rngd is only needed in case you want to pipe in random numbers from an external rng
• this is a fringe case, because random numbers in CPUs (even virtualized) are good these days
• original OS images don't have pre-enabled rngd, so requiring it would involve a lot of effort on the CSP side that may have very little demand
• finally, people can always create their own image with pre-enabled rngd (and if they want their external rng, they might want this amount of control anyway)

[mbuechse]

@artificial-intelligence I have another question. Shall we relax the recommendations on image properties to only apply for images with visibility "public"? The image metadata check seems to only check those as well.

[mbuechse]

@artificial-intelligence I've been told that images with visibility private cannot be controlled by the operator, so it's no use regulating those.