Revises the Node CI

[Berkmann18]

As it's now unwise to get Cypress to target the production URL over a local one (especially in PRs), it now tests against http://localhost:1234 built by the CI itself.

[Berkmann18]

I have a feeling, it would need Conv2D kernel (#43) to work properly.

[amirhmk]

@Berkmann18 I think for the dev test to pass you have to change

cy.visit('/dev'); -> cy.visit('/dev.html');

[Berkmann18]

@amirhmk Does that work on your hand?