Tag GPX file with most specific MIME type, address #77

This should work-around the Firefox OS's email app's bug relating to
text/plain attachments while also being more correct and allowing
receiving apps to know the MIME type without using system local
extension MIME maps.
Merge pull request #78 from asutherland/email-mime-type

Tag GPX file with most specific MIME type, address #77
fixing bug #76 - Elapsed Time depending on timezone
Merge branch 'develop' of https://github.com/nicodel/Run-Bike-Hike into develop
changing version
Merge pull request #74 from Bonbadil/develop

Display hours on graph again (an JSHint track-view.js).
I will undo jshint related changes
uploading first spanish translations
adding features to changlog
jshint - controller.js
jshint - event.js
jshint - app.js
jshint - models/chrono.js
jshint - models/config.js
jshint - models/db.js
jshint - models/export_tracks.js
jshint - models/gpx.js
jshint - models/sdcard.js
jshint - models/share.js
jshint - models/tracks.js
cleaning unecessary files in js/models