Simplify installation on AppVeyor CI

[brodycj]

Platforms affected

iOS

What does this PR do?

• Simplify installation on AppVeyor CI now that uncrustify is gone, should now succeed on deprecated Node.js 4 version

What testing has been done on this change?

• Check that AppVeyor CI succeeds on all Node.js versions in appveyor.yml including deprecatd Node.js version

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.

[codecov-io]

Codecov Report

Merging #383 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #383   +/-   ##
=======================================
  Coverage   63.86%   63.86%           
=======================================
  Files          14       14           
  Lines        1702     1702           
  Branches      286      286           
=======================================
  Hits         1087     1087           
  Misses        615      615

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