Squashed commit of the following:

commit 997c1138f549766d797f1ba6da26e1e8394387e2
Author: emeric <itmfr@yahoo.fr>
Date:   Sat Jan 10 17:50:20 2015 +0100

    Implemented save, load and delete playlists

commit bee08a16b544bb21785c45f083ab7c10e65bfa6e
Author: emeric <itmfr@yahoo.fr>
Date:   Thu Jan 8 23:46:43 2015 +0100

    Reworked the database code layout in order to add playlists

src/database/User.hpp

@@ -20,7 +20,9 @@
 #ifndef DATABASE_USER_HPP
 #define DATABASE_USER_HPP
 
+#include <vector>
 
+#include <Wt/Dbo/Dbo>
 #include <Wt/Auth/Dbo/AuthInfo>
 
 namespace Database {
@@ -28,6 +30,8 @@ namespace Database {
 class User;
 typedef Wt::Auth::Dbo::AuthInfo<User> AuthInfo;
 
+class Playlist;
+
 class User {
 
 	public:
@@ -68,6 +72,7 @@ class User {
 				Wt::Dbo::field(a, _isAdmin, "admin");
 				Wt::Dbo::field(a, _audioBitrate, "audio_bitrate");
 				Wt::Dbo::field(a, _videoBitrate, "video_bitrate");
+				Wt::Dbo::hasMany(a, _playlists, Wt::Dbo::ManyToOne, "user");
 			}
 
 	private:
@@ -87,6 +92,8 @@ class User {
 		int		_audioBitrate;
 		int		_videoBitrate;
 
+		Wt::Dbo::collection< Wt::Dbo::ptr<Playlist> > _playlists;
+
 };
 
 } // namespace Databas'