use cstate colors instead of "ok"/"warning"-color for Incident severities

[MirMiz]

Is your feature request related to a problem? Please describe.
the incident history on the Main page shows the status of the incident always in red color -- indepentend of the incident's serverity
the red color used, is the "error" color.

Describe the solution you'd like

1. it would be nice to indicate the Severity not only by icon, but also by the severity's color chosen in config.yml (and used in the component list above as well)
2. the three icons "■, ▲, ◆" are nice. They lack an explanation, though. Therefore, writing the translation of the serverity next to them would be helpful for the user.