GitHub actions integration

[jensstalder]

Semantic versioning

This PR is a Patch (bugfix, hotfix, without adding new stuff)

Generall things to consider

• I have read the CONTRIBUTING.md document.
• If my change requires documentation, I added it already.
• I have added tests to cover all my changes.
• All new and existing tests pass.

List of issues related to this PR

• closes Move to github actions and pure Node.js linting #163

Problem description
Currently there are a couple of dependencies to dotnet and travis that can be replaced with github actions ever since it has been introduced. This would make things more accessible to web-developers by leveraging node.js instead which is already in use anyhow.

Desired Solution

Removal of Jenkins pipeline
Creating appropriate github actions
Rewrite tests with node.js

[jensstalder]

Looks like some of the docs/docs/html changes have made it into this branch. I/we will need to update theses back to the master representation, since these files should not change based on a PR. (only when release version tag gets set).

[jensstalder]

Just noticed that there is a docker-compose.yml file that sets-up the dotnet testing within a docker container. Intresting.

[koffeinfrei]

• package-lock.json is outdated.
• Should we add an .nvmrc (or any other alternative you prefer) to lock the node version?

Otherwise LGTM 👍