make ondemand and ondemand_dex package installs idempotent

[sjpb]

The current defaults for ondemand_package and ondemand_dex_package aren't idempotent. This is problematic, as there is no way to get the behaviour of "install whatever the latest version is, then don't upgrade it on a rerun unless explicitly asked to". Note that that behaviour is the default yum/dnf behaviour.

This PR changes the behaviour of the defaults to be idempotent (hopefully that change is acceptable), and makes it so using latest is required to get an upgrade on an already-installed package.

The README changes have been made incorporating #215

[johrstrom]

Sorry for the delay - I was on vacation for a bit and now just have to remember that this is still on my plate- which it is.

I'll try to get this merged as soon as I can.

[johrstrom]

I'm looking into why tests are failing.

[johrstrom]

I cannot commit to your branch directly, so I cannot supply this patch myself. This is the diff you need to get the tests to work correctly. We have a test case for upgrading and as this changes the logic a bit, we need to account for that.

diff.txt

[sjpb]

Sorry for the delay, was away.

[johrstrom]

Thanks for the update, no issues on your lag if there are no issues with my lag.

I am currently wondering if this can go now or if I should wait for 3.1 as it's a behavior change. Not a big one, but could impact current users. 3.1 is right around the corner, so it won't be long, but the fact that galaxy is (was) weird complicates it further.

[sjpb]

Given it is a behaviour change, personally I'm happy to wait for it (especially if that's coming soon). Its not a blocker for me, but it will make behaviour easier to work with.

[johrstrom]

3.1 is being released today, so I'm going to merge this now for that release. Thanks again for the contribution!