Vertical Speed & User Homepage

Few improvements:

• On the user homepage the date of the track is shown instead of the upload date;
• It's possible to change or set the track date in the info panel on the right;
• In flying mode the controls disappears;
• On the analyze page there is a new graph, called "Vertical Speed" (height gain per hour); this graph is avalaible for tracks that have both time and elevation;
  
• We removed the timeout that was preventing slow uploads to finish correctly;
• We did various style improvements;

Here an example of the vertical speed graph