fix: wrong url of css and scripts when opening portal in issue #89

[cedric-beurtheret-jcd]

In issue #87, modifying the config.ts file was not sufficient, and the problem was not solved, because of page generation through the template engine. So for issue #89, I had to change:

• the template index.html
• the io.phasetwo.portal.PortalResourceProvider.java class
• the build-mvn script in the package.json

Then the base url is constructed at runtime by the PortalResourceProvider and injected in template.

[xgp]

@cedric-beurtheret-jcd thanks for the PR. Sorry I missed this, but I didn't have notifications for PRs setup right.