Make ebs_raid resource usable without a snapshots attribute

[mkantor]

The fix is simple: change empty value for snapshot_id from '' to nil.

Before this change, using the ebs_raid resource without a snapshots attribute produced the following error:

Aws::EC2::Errors::MissingParameter
The request must contain the parameter size/snapshot

I plucked this out of #130 since it's the minimum change required to make ebs_raid usable again. The encryption stuff is great, but orthogonal to this fix.

Fixes #118.

[miketheman]

Thanks for your effort on picking this out!

[DrMerlin]

Hey, @miketheman- any reason that the original pull request was not merged? Is there anything wrong with it? There are no negative comments in the PR.

[miketheman]

@DrMerlin Sure - the PR suggested did both a fix and an enhancement - and I was trying to get all bugs that I could released in a bugfix-only release.

For that one, I'd suggest rebasing against current master, and squashing commits down to reflect the addition of the encryption to be considered for an enhancement release.

Does that make sense?

[DrMerlin]

@miketheman
With all due respect- #130 contained two fixes and no enhancements. The enhancement was already added through #114 on 6 Apr, but it was broken. #130 fixed both errors associated with creating encrypted EBS RAIDs, but isn't an enhancement itself.

[miketheman]

@DrMerlin I'm sorry if I missed that - but reading through the code, it appears to introduce the encrypted behavior.

Looking at the history of the ebs_raid.rb file, I cannot see that these cahnges ever made it into master. Those encryption changes appear to be scoped to the ebs_volume resource, not the ebs_raid one - that's the enhancement I'm referring to.