Drop-in configuration for the MyMo kiosk.

Files matching *.conf are sourced after /etc/mymo-kiosk.conf, in
lexical order — later files override earlier ones. Application packages
declare their URL here (e.g. 50-mymo.conf, shipped and removed with the
application package). Put site-local overrides in 99-local.conf.

Recognised variables: KIOSK_URL, KIOSK_STATE_DIR.
