Add flag to return top result instead of random result for image/animate/youtube.

This keeps the default functionality as random result.
Tighten regex for !docs trigger.

Current regex catches !docscontrib. New regex requires a space after !docs.
Merge pull request #31 from lagbox/fix/docs-regex

Tighten regex for !docs trigger.
Merge pull request #30 from lagbox/feature/more-than-just-random

Add flag to return top result for image/animate/youtube
Merge branch 'master' into update/triggers