Fixes issue: #582 'I can skip/backward 15 seconds from a button in the play menu
Lowercase all resources in book.resources

This is not following the standard strictly, but since some books are
produced with filename case-issues, this fix is sadly necessary. It's very
unlikely that two files with the same filename but different casing will
occur.
Merge pull request #630 from saebekassebil/lowercase-2.1.x

Lowercase all resources in book.resources
removed loggin
Code clean
Code clean
Merge pull request #631 from Notalib/skip15

Fixes issue: #582 'I can skip/backward 15 seconds from a button in the p...
Fix faulty reference to @section in segment
Merge pull request #632 from saebekassebil/lowercase

Fix faulty reference to @section in segment
Merge branch '2.1.x'
Merge remote-tracking branch 'notalib/master'
refactor