add section for scheduling services

with two examples:
Doodle (proprietary) and Dudle (free)
resize doodle and dudle images
fix i18n class for Scheduling header
add translation stubs for i18n-scheduling and i18n-dudle-desc
use higher quality image for Doodle, thanks to Zegnat
Merge pull request #663 from xrchz/master

add section for scheduling services