add missing sleep images and translations

Plugins/Wox.Plugin.Sys/Languages/en.xaml

@@ -11,6 +11,7 @@
     <system:String x:Key="wox_plugin_sys_exit">Close Wox</system:String>
     <system:String x:Key="wox_plugin_sys_restart">Restart Wox</system:String>
     <system:String x:Key="wox_plugin_sys_setting">Tweak this app</system:String>
+    <system:String x:Key="wox_plugin_sys_sleep">Put computer to sleep</system:String>
 
     <system:String x:Key="wox_plugin_sys_plugin_name">System Commands</system:String>
     <system:String x:Key="wox_plugin_sys_plugin_description">Provide System related commands. e.g. shutdown,lock,setting etc.</system:String>

Plugins/Wox.Plugin.Sys/Languages/zh-cn.xaml

@@ -11,6 +11,7 @@
     <system:String x:Key="wox_plugin_sys_exit">退出Wox</system:String>
     <system:String x:Key="wox_plugin_sys_restart">重启Wox</system:String>
     <system:String x:Key="wox_plugin_sys_setting">设置</system:String>
+    <system:String x:Key="wox_plugin_sys_sleep">休眠这台电脑</system:String>
 
     <system:String x:Key="wox_plugin_sys_plugin_name">系统命令</system:String>
     <system:String x:Key="wox_plugin_sys_plugin_description">系统系统相关的命令。例如，关机，锁定，设置等</system:String>

Plugins/Wox.Plugin.Sys/Languages/zh-tw.xaml

@@ -11,6 +11,7 @@
     <system:String x:Key="wox_plugin_sys_exit">退出Wox</system:String>
     <system:String x:Key="wox_plugin_sys_restart">重啟Wox</system:String>
     <system:String x:Key="wox_plugin_sys_setting">設置</system:String>
+    <system:String x:Key="wox_plugin_sys_sleep">休眠这台电脑</system:String>
 
     <system:String x:Key="wox_plugin_sys_plugin_name">系統命令</system:String>
     <system:String x:Key="wox_plugin_sys_plugin_description">系統系統相關的命令。例如，關機，鎖定，設置等</system:String>

Plugins/Wox.Plugin.Sys/Sys.cs

@@ -95,7 +95,7 @@ namespace Wox.Plugin.Sys
                 new Result
                 {
                     Title = "Sleep",
-                    SubTitle = "Put computer to sleep",
+                    SubTitle = context.API.GetTranslation("wox_plugin_sys_sleep"),
                     Score = 100,
                     IcoPath = "Images\\sleep.png",
                     Action = (c) => Application.SetSuspendState(PowerState.Suspend, false, false)

Plugins/Wox.Plugin.Sys/Wox.Plugin.Sys.csproj

@@ -65,6 +65,9 @@
     </ProjectReference>
   </ItemGroup>
   <ItemGroup>
+    <Content Include="Images\sleep.png">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
     <Content Include="Languages\en.xaml">
       <Generator>MSBuild:Compile</Generator>
       <SubType>Designer</SubType>