Moved backend docs from Installation.md to README.md and added more details regarding buiding/deploying the backend services

Removed pre-built Angular distro and freeze version numbers to support reproducible builds of the UI.

Remove virtual host support and add support for path-based discrimination in reverse proxy.

Moved Proxy readme into its own directory and updated documentation to reflect that the base REST API URL must be provided.

Provide option to set web services URL either at build time or at runtime. At runtime the setting can be provided either as an env variable or cli argument