Tickets - Priority, Severity options

+ Severity indicated via new character indicator and color of ticket icon on ticket list
+ Priority indicated via new priority icon and color on ticket list
+ Indexed as integers to provide sorting and maintain language neutral
index
+ Colours and indicator text controlled through CSS classes priority-<x> & severity-<x>
+ UITicketTest created to generate tickets of all types to ease debugging
Adjust priority & severity CSS

- Severity: more severe are ROY, less severe are GB
- Replaced first-letter of severity with S# and show # dots
- Priority: higher priorityare RO, lower priority is B

I really like the 'C, 'CA' idea but that will definitely lead to translation questions. The S# approach will still generate the same complaints, but at least it is more generic.
Remove S# text, set severity in tooltip
Merged #157 "Add Priority & Severity fields to the ticket model"