Previously, index.html used absolute paths to load its CSS and
JavaScript. This meant that it had to be deployed to /. This commit
updates the HTML to use relative paths for its CSS and JavaScript,
thereby ensuring that they can be loaded irrespective of the context
path to which the application is deployed.
Closes gh-1988
* For a jar deployment add classpath:static/index.html
(works via Spring MVC mapping)
* For a war the same thing works, but so does adding
index.html to src/main/webapp (works via container
default servlet)
[Fixes#54092261] [bs-252]
