Migrate http -> https for nodered.org

[Rotzbua]

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Proposed changes

Migrate http://nodered.org to secure https://nodered.org since https is the new default.

Checklist

• I have read the contribution guidelines
• For non-bugfix PRs, I have discussed this change on the forum/slack team.
• I have run grunt to verify the unit tests pass
• I have added suitable unit tests to cover the new/changed functionality

[knolleary]

I'm satisified the test failure is one of the random timing failures, rather than anything related to this PR.

Given this is useful housekeeping, I'm going to merge now to include in 3.1.