Create utils sub-module

New utils sub-module contains the duckduckgo functionality for getting
the definition of a word.
Add scheduler utility for irregular feed updates

Irregular scheduler is able to pick a random point in a day to schedule
a feed update. If that point has not arrived the previous day's
scheduled update is used instead.
New scheduler for periodic feed updates

Regular feed update schedule released new feed items after N hours,
offset into the day by M hours. Always winds back to previous release
time, even if that was on a prior day.