Update node version

[hicom150]

• Update dependencies.
• Fixed some ESLint errors.
• Replace libxml-xsd with libxmljs [1]
• Add support for all nodejs lts versions (6, 8, 10)

[1] libxml-xsd is obsolete and it doesn't support nodejs 10 in the other hand, libxmljs can be used to check xsd schemas.

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[johnjbarton]

I think putting each of these in a separate PR will make maintenance easier. We typically merge all the commits in a PR. If any one of these needs to be reverted we'll have to revert them all.

That said I'll leave it to joeyparrish to decide.

It does not look like Travis is connected for this repo.

[hicom150]

As @johnjbarton suggested I've divided this in separate PRs

• Replace libxml-xsd with libxmljs test: replace libxml-xsd in favor of libxmljs #166
• Add support for all nodejs lts versions (8, 10) test: replace libxml-xsd in favor of libxmljs #166
• Update ESLint dependencies and fix linting errors style: update eslint dependencies #167