[feature] path to logo in settings file

[jibe-b]

Logos and pictures could be in the settings file to make the config even easier.

For example, logo is in:

./client/head.html
<img src="/logo/openki.png" alt="Openki logo">
./imports/ui/pages/kiosk/kiosk.html
<img src="/logo/openki.png" class="kiosk-logo kiosk-logo-openki">

I'll have a look at meteor templates (not done much with meteorjs until now) and may do it.