add bed marker icon from faithful pack

Taken from the Faithful 32 texture pack:
http://www.minecraftforum.net/viewtopic.php?f=25&t=77442

overviewer_core/assetmanager.py

@@ -87,6 +87,7 @@ directory.
         dump['CONST']['image'] = {
                 'defaultMarker':    'signpost.png',
                 'signMarker':       'signpost_icon.png',
+                'bedMarker':        'bed.png',
                 'compass':          'compass_upper-left.png',
                 'spawnMarker':      'http://google-maps-icons.googlecode.com/files/home.png',
                 'queryMarker':      'http://google-maps-icons.googlecode.com/files/regroup.png'

overviewer_core/data/js_src/views.js

@@ -312,6 +312,8 @@ overviewer.views.SignControlView = Backbone.View.extend({
                     if (entity['id'] == 'Player') {
                         iconURL = "http://overviewer.org/avatar/"
                             + entity['EntityId'];
+                    } else if (entity['id'] == 'PlayerSpawn') {
+                        iconURL = overviewerConfig.CONST.image.bedMarker;
                     } else if (entity['id'] == 'Sign') {
                         iconURL = overviewerConfig.CONST.image.signMarker;
                     } else {