Add Device:Info for android and use it in report a bug infomessage.

Move local function getCodename to top, use android.app.activity.sdkVersion directly,
instead of relying on Device.firmware_rev

frontend/ui/elements/common_info_menu_table.lua

@@ -53,10 +53,14 @@ common_info.report_bug = {
     text = _("Report a bug"),
     keep_menu_open = true,
     callback = function()
-        local model = Device.model
+        local device = Device.model
+        if Device:isAndroid() then
+            device = Device:info()
+        end
+
         UIManager:show(InfoMessage:new{
             text = T(_("Please report bugs to \nhttps://github.com/koreader/koreader/issues\n\nVersion:\n%1\n\nDetected device:\n%2"),
-                version, model),
+                version, device),
         })
     end
 }