Don't call @_setCurrentSegment when it's not needed

We don't need to call @_setCurrentSegment when calling either @navigate
or @seekSegmentOffset, since @seekSegmentOffset already call this method
for us.
Show publication year and media format in book details
Don't read up the cover-image of books
Add aria labels to player controls
Meaningful labels for playback rate settings
Only focus on pause/play button when its state is changed
Make loading messages role='alert'
Fix faulty reference to @section in segment
Remove unused images files.
Merge pull request #632 from saebekassebil/lowercase

Fix faulty reference to @section in segment
Add list images with more contrast
Merge pull request #622 from saebekassebil/dblcurseg

Don't call @_setCurrentSegment when it's not needed
Merge branch '2.1.x'
Merge pull request #634 from mzedeler/remove-unused-images

Remove unused images files
Remove notabs task, and simplify some Cakefile code
Add uglifyjs as a dependency and use the local version for minifying
Only send one GetItemById request when viewing book details
Merge pull request #623 from saebekassebil/bookinfo

Show publication year and media format in book details
Refactor in catalog.coffee
Merge pull request #627 from saebekassebil/a11y

Fixed some a11y issues