Use popover to show parse errors
Colour code the results to show complete, fail, skipped.

Also show status for completed modules in the popover.
Documented the migration framework
Make migration code aware of bookshelve changes.

This basically apply the relevant bits of 4190d2 rebased on a
new master.
Auto-scroll migration log to the bottom, styling.

Skipped modules are now white rather than yellow. More neutral.
Log will auto-scroll so the last module is always visible. It will
however only scroll if the window is at the bottom already, allowing
the user to scroll up without interference.
Indicate when migration is finished.
Document the head migration
Merge pull request #150 from oerpub/migration-improvements-episode1-v2

Migration improvements