Make the integration and example tests compatible with the latest version of npm

[erikbarke]

The integration tests and some of the examples only run correctly when installed with older versions of npm, for example npm@3.10.10 on the CI servers.

Issues when installing with npm@6.4.1:

• typescript@3.1.1 gets installed for examples/typescript-1.6.2
• typescript@3.1.1 gets installed for tests/integration-1.8.10
• The module [rgb-color] can't be resolved in a test in tests/integration-latest

[erikbarke]

@glvangorp, @vidartf, could you help me out with this issue?

A clean npm install crashes completely in examples/typescript-1.6.2 with "no such file or directory" for @types/acorn when installing with npm@6.4.1 if I try to lock the typescript version to 1.6.2 in package.lock.json 🤔

If I don't lock the typescript version 3.1.1 gets installed even though 1.6.2 is specified in package.json...