README: mention reporting warning status
Database: add patterns and note to jobconfig table

This commit updates the schema file and also adds an update
script to apply this change to an existing database.
Store: read and write new jobconfig columns
Web: allow configuration of patterns and note
Store: check job status patterns on logging finish
Templ: add explanations for the new options
README: update documentation of job configuration

Expanded the existing documentation to explain what the
grace period and time-out are, and added a new paragraph
about the status pattern matches.