add support for multiple licensenses in one projekt

[derpeter]

it should be possible to render outros with different licensens for each cc license type used in the schedule.

it could be done by label the logo areas in the svg and replace the image before rendering the outro.
There for we also need a new naming for the outro file. There are to option:

a) render one outro per license e.g. cc-by-sa-outro.ts
b) render one outro per event e.g. 2342-outro.ts

If do a) the tracker / encoding worker needs to take care to map a license to a talk
if we do b) we render more files but would also have the option to change more things in the outro like adding the talk title and speaker name again

We have a ticket in the vcfb schedule thats would need this feature.

[derpeter]

turns out b) is already supported from tracker / CRS side