Fixes: #550

Hi,

this PR enables potential users to provide their own Welcome page.

With the flag --web-template-path=<path>, you can specify the path to your custom welcome page.

The structure of the folder should be like this:

web/
  index.html
  xyz.html
  static/
      main.css
      main.js

I use c.HTML to serve the custom welcome page, this means we have full access to the go-template engine

The rules are: Every file with html ending will be picked up. This is useful if you want to create templates and include them in the main index.html file (see my example). But only the index.html will be served!

Static files (css, js or pics) should be saved into the static folder. I check the code, if the static folder if present to serve this.

Currently, their is no support for variables in the template.

If everybody like this, I will extend the enable the helm chart too.

Example:

Looking for your feedback!