webui: Initial commit
webui: Add web-scanner command; fix globals in scanapi
webui: Begin work on configuration API
webui: Refactoring, minimal workflow API implementation
webui: Update AngularJS to 1.0.8
webui: Add 'first_page' option to template
webui: Implement data-binding for configuration template
webui: Implement configuration update
Modifications to Workflow API

- The object is now responsible for setting the time of first capture
- Fix typo 'flip_target_page'
web: Update NOTES
web: Complete overhaul of the API
web: More work on largely mode-independent parts
webplugin: Add testsuite
web: Adjust configuration handling
web: Use pathlib; other fixes for updated master
web: Rename 'database.py' to 'persistence.py'
web: Fix some remaining spots from database->persistence renaming
web: Cache workflow instances in global dictionary
web: Use decorator for caching
web: Use URLs instead of filenames for references to images in views