added gadget_info json file

bt5/erp5_web_editor_demo/SkinTemplateItem/portal_skins/erp5_rjs_interface_gadgets/gadget_info.json.xml

+<?xml version="1.0"?>
+<ZopeData>
+  <record id="1" aka="AAAAAAAAAAE=">
+    <pickle>
+      <global name="File" module="OFS.Image"/>
+    </pickle>
+    <pickle>
+      <dictionary>
+        <item>
+            <key> <string>_EtagSupport__etag</string> </key>
+            <value> <string>ts41295189.16</string> </value>
+        </item>
+        <item>
+            <key> <string>__name__</string> </key>
+            <value> <string>gadget_info.json</string> </value>
+        </item>
+        <item>
+            <key> <string>content_type</string> </key>
+            <value> <string>application/octet-stream</string> </value>
+        </item>
+        <item>
+            <key> <string>data</string> </key>
+            <value> <string>{\n
+"Bootstrap3 Editor" : "interface_gadget_bootstrap3_wysiwyg.html", \n
+"Tinymce Editor" : "interface_gadget_tinymce.html",\n
+"CKEditor" : "interface_gadget_ckeditor.html",\n
+"Handsontable Spreadsheet" : "interface_gadget_handsontable.html",\n
+"Slickgrid Spreadsheet" : "interface_gadget_slickgrid.html",\n
+"Chartjs Graph" : "interface_gadget_chartjs.html",\n
+"ChartistJS Graph" : "interface_gadget_chartistjs.html"\n
+}\n
+\n
+</string> </value>
+        </item>
+        <item>
+            <key> <string>precondition</string> </key>
+            <value> <string></string> </value>
+        </item>
+        <item>
+            <key> <string>size</string> </key>
+            <value> <int>406</int> </value>
+        </item>
+        <item>
+            <key> <string>title</string> </key>
+            <value> <string>gadget_info.json</string> </value>
+        </item>
+      </dictionary>
+    </pickle>
+  </record>
+</ZopeData>