Bug 910446: Handle duration changes in Music app

With the landing of bug 831224, the duration of MP3 files is
computed while they are playing, and updated accordingly. If
this happens, we distribute a 'durationchange' event to the
related apps.

With this patch, we handle 'durationchange' in the Music app.
All we have to do is to update the displayed duration and ensure
that the end timeout triggers at the end of the track.

Signed-off-by: Thomas Zimmermann <tdz@users.sourceforge.net>
bug 900838: [System] play poweron video after first repaint
Bug 907672 - [HD][Settings] Locked Wifi Connection icon jumps
Bug 907729 - [HD][FTU] Locked Wifi Icons Jump when connecting
Bug 802643 - Remove activity workaround in email app
Bug 911875 - [Homescreen] When user select icon and press home key, selected color is shown on icon
Bug 912060 - Better and more tested call screen toggling
Bug 912184: use require() to load shared/js files
Merge pull request #11917 from rexboy7/fix-bug900838

bug 900838: [System] play poweron video after first repaint
Bug 903915 - [Flatfish][Homescreen] add support for large device
Merge pull request #11477 from gasolin/tabhomemq

Bug 903915 - [Flatfish][Homescreen] add support for large device, r=crdlc
Bug 909255 - Remeber window disposition activity caller
Merge pull request #11903 from crdlc/bug-911875

Bug 911875 - [Homescreen] When user select icon and press home key, selected color is shown on icon
Merge pull request #11861 from alivedise/bugzilla/909255/window-disposition-activity

Bug 909255 - Remeber window disposition activity caller, r=timdream
Merge pull request #11894 from alivedise/bugzilla/802643/remove-workaround-in-email-app

Bug 802643 - Remove activity workaround in email app, r=asuth
Bug 907941 - gaia-ui-tests-pushbot (see bug)
Revert "Bug 906756 - Algorithms for merging givenName and familyName changed."

This reverts commit 9e737ce855b02ab60a9ab8b87f6a1d6ffa1a191c.
Merge pull request #11892 from pivanov/bug-907729

Bug 907729 - [HD][FTU] Locked Wifi Icons Jump when connecting r=samjoch
Merge pull request #11891 from pivanov/bug-907672

Bug 907672 - [HD][Settings] Locked Wifi Connection icon jumps r=samjoch
Bug 907941 - gaia-ui-tests-pushbot (see bug)