Improve the details provided by the "Severities vectors" tab in VCIO "Vulnerability details"

First, a quick and simple one: please change the tab label from "Severities vectors" to "Severity metrics".

Objective: Make the various scores more useful by providing information about their origin, and reinforcing the scores that we display on the "essentials" tab.

The various details can be greatly improved by providing and displaying, for each severity:
* origin name
* (optionally) origin URL if available.
* the CVSS numeric score

Provide these details in the v2 API.

We should consider and discuss whether we would like to expose the Weight assigned to each origin, which might be useful (but alternatively might be confusing or distracting). A benefit could be to support the value that we provide as Weighted Severity on the Essentials tab.