Update default settings before testing on Travis

When testing on a clean build, default settings need to be initialized.
Update gems
Remove wikipedia-client gem
Remove Commontator models and controllers

Re-insert them if you need the ones used by the engine.
Standardise all references to all_interrelated_notes_and_features
Fix cropped last lines in paragraph (parallel mode)
Ajaxify user menu and flash notices to make page caching possible

Unable to get tests working, even using capybara-webkit.
Fix feature breadcrumb
Change inline instructions to braced paragraphs e.g. {cap: Caption}
Fix Evernote text scanning
Remove introduction from body text after saving it
Add edit distance to version statistics
Fix distance to take account of skipped versions

Reify the last version rather than relying on title_was and body_was.
Use real distance when deciding whether to save a new version

When deciding whether to store a version, we need to compare the current
text with the latest stored text. (When storing distance, we do the
comparison after we have saved a version, so if a version is not saved
it is ignored.)
Fix removal of inline instruction
Update gems
Remove Commontator helpers

Not required unless we're patching them.
Refactor controllers
Refactor models
Rename books admin metadata_missing to missing_metadata