Next, you will use the Policy Tool to 
create a policy file named exampleraypolicy
and in it grant a permission to code from 
a signed JAR file. 
The JAR file must have been signed using the 
private key corresponding to the public key imported into Ray's
keystore (exampleraystore) in the previous step.
The certificate containing the public key is aliased by susan in
the keystore. We will grant such code permission to read any file in the  
C:\TestData\ directory.
The steps are: