Removed Node.js v4, added Node.js v10

[Kazuki-Nakanishi]

Types of changes

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

Proposed changes

As Node.js version4 is no longer supported, removed it.
Added version 10 and matrix include description.

The above fix is following this pull request.
node-red/node-red#1708

Checklist

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

[coveralls]

Coverage remained the same at 76.375% when pulling 2e41629 on node-red-hitachi:nodejs-version into 5a44627 on node-red:master.