Bugfix - caches weren't getting cleared/updated on publish.

Upgrade templates for mkdocs-material version 5.1.1

Bugfix for ExceptionSubscriber - now loads RedirectResponse class correctly.

(Version bump, 1.1.2 didn't include the commit!)

Bugfix for ExceptionSubscriber - now loads RedirectResponse class correctly.

Minor CSS fix for MkDocs generated page footers.

Adds two new commands for managing the cached git repositories.

• ./bin/console repo:clear book/lang - Removes the cached repository information from the filesystem.
• ./bin/console repo:pull book/lang - Performs a git pull against the cached repository to pull updated information from upstream.

Also adjusts some styling in-app.

MkDocs requirement bumped to 1.0.4.

Tags will use a semver style version from here on!