CB-11913 - Re-fix appveyor.yml to use specific node versions

[shazron]

Platforms affected

All

What does this PR do?

Fix appveyor.yml node versions, they were incorrect previously

What testing has been done on this change?

The test will be on Appveyor (automated with this PR)

Checklist

• Reported an issue in the JIRA database
• Commit message follows the format: "CB-3232: (android) Fix bug with resolving file paths", where CB-xxxx is the JIRA ID & "android" is the platform affected.
• Added automated test coverage as appropriate for this change.

[shazron]

Now that I've got appveyor node versions "working", it reflects the node 6 failures on Travis. Now to get node 6 working (npm link shenanigans).

[shazron]

Might be related: npm/npm#9633

[shazron]

Nah its npm/npm#10343

[stevengill]

hows it going on this?

[shazron]

@stevengill unfortunately npm/npm#9633 strikes its head (see AppVeyor failure). Usually running npm install again fixes it, but once the first npm install fails it just fails the build

[shazron]

@stevengill since yarn works flawlessly on node 6 the alternative is, put all the install commands in a script and use yarn when we detect node 6. Kinda like my script here: npm/npm#10343 (comment)

[shazron]

Final fix that worked: downgrade to npm@2