[VS Addin] Fix several issues with debugging PPAPI plugins

visual_studio/NativeClientVSAddIn/NativeClientVSAddIn/Strings.resx

 <?xml version="1.0" encoding="utf-8"?>
 <root>
   <!-- 
     Microsoft ResX Schema 
     
     Version 2.0
     
     The primary goals of this format is to allow a simple XML format 
     that is mostly human readable. The generation and parsing of the 
     various data types are done through the TypeConverter classes 
@@ skipping 133 matching lines @@
   <data name="NaClLoaderFlag" xml:space="preserve">
     <value>--type=nacl-loader</value>
   </data>
   <data name="NaClProcessName" xml:space="preserve">
     <value>nacl64.exe</value>
   </data>
   <data name="PepperPlatformName" xml:space="preserve">
     <value>PPAPI</value>
   </data>
   <data name="PepperProcessPluginFlagFormat" xml:space="preserve">
-    <value>--register-pepper-plugins="{0};application/x-nacl"</value>
+    <value>--register-pepper-plugins="{0};application/x-ppapi"</value>
     <comment>Argument is plug-in assembly's path</comment>
   </data>
   <data name="PNaClPlatformName" xml:space="preserve">
     <value>PNaCl</value>
   </data>
   <data name="SDKPathEnvironmentVariable" xml:space="preserve">
     <value>NACL_SDK_ROOT</value>
   </data>
   <data name="SDKPathNotSetError" xml:space="preserve">
     <value>NaCl SDK Root is not set in project properties! Cannot run NaCl functionality.</value>
@@ skipping 15 matching lines @@
   <data name="WebServerStartMessage" xml:space="preserve">
     <value>Launching web server...</value>
   </data>
   <data name="WebServerStopMessage" xml:space="preserve">
     <value>Killing web server...</value>
   </data>
   <data name="NaClARMPlatformName" xml:space="preserve">
     <value>NaClARM</value>
   </data>
 </root>