Render a container for chapter-info in progressbar

A static solution for applying CSS.
Needs to be refactored:
So far, the active Chapter, which should be displayed above the
progress bar, is unreachable outside the chapter module.
The data of the current chapter should be stored in a central place.
Responsive layout for progress bar and its info items

The chapter title as well as the duration info is displayed above the
progress bar and will adapt to different screen solutions.
Set color and background color for chapter badge
fix character encoding issue in _progressbar.scss
set current chapter title and badge

Reorganize code in app module addBehaviour function.
Module set-up is separated from tab instantiation.

Chapter module now initialized currentChapter with 0 instead of -1.

Progressbar module keeps references to chapter module as well as chapter
badge and chapter title elements.
Its update function then will update both elements with the current
chapter data.
Its constructor expects only the timeline as the params object was not
needed.

related: https://trello.com/c/MqPNx3ms/87-progressbar-kapitel-anzeigen
fix tab layout by resetting base font size

Flex box rules…. in a way.
minor cleanup in chapter module
Merge pull request #197 from podlove/progressbar-changes

Progressbar changes