added batch for creating a new key

keys/generate_new_key.bat

@@ -0,0 +1,13 @@
+@ECHO OFF
+IF EXIST "C:\Program Files\Microsoft SDKs\Windows\v7.0\Bin\sn.exe" GOTO FOUND
+goto USEPATH
+
+:FOUND
+"C:\Program Files\Microsoft SDKs\Windows\v7.0\Bin\sn.exe" -k %~dp0\Google.ProtocolBuffers.snk 
+GOTO EXIT
+
+:USEPATH
+sn.exe -k %~dp0\Google.ProtocolBuffers.snk 
+GOTO EXIT
+
+:EXIT