Implement simple migration view.

This includes a table migration as well, for removing captions on tables.
Merge branch 'master' into migration-framework
Move migration route into gh-book.
Moved the migration view and template into gh-book.
Greatly improve progress indication.
Use a sequential migration method.

This avoids getting the browser bogged down with too many asynchronous tasks.
Merge pull request #121 from oerpub/migration-framework

Implement simple migration view.