Update cypress to last version

[lossendae]

What problem does this feature solve?

Can the cypress plugin be updated to use the last cypress.io version (3.0.1)

Since it's a major version and vue-cli is still in beta, this will allow users to be in sync with the documentation available on Cypress.io website.

What does the proposed API look like?

The changelog is available here: https://docs.cypress.io/guides/references/changelog.html#3-0-0