Create FeatureDrawing.js

 *  .. class:: FeatureDrawing(config)
 *
 * Provides a menu to draw on layers given in config.
 * <ul>
 *     <li>Based on a WMS
 *     <li>You can pass as much as layers as you want.
 *     Currently only POINT, LINE and POLYGON layers are supported.</li>
 *     <li>You can allow text add to your layer (here symoblized by a checkbox with the Ext id given on config in
 *     'labelPromptCheckboxId'</li>
 *
 * The expected 'editableLayers' parameter expected structure is:
 *  
 *  editableLayers: [
 {
     layer: THE VECTOR LAYER TO DRAW ON,
     layerWMS: THE LAYER IN WMS FORM TO ALLOW LAYER REFRESH,
     saveStrategy: THE SAVE STRATEGY OF VECTOR LAYER,
     type: THE TYPE OF LAYER gxp.plugins.FeatureDrawingConstants.*
 },
 ...
 ]