Please review: Signed Modular JAR file support

[Sean Mullan]

I have implemented support for signed modular jars. This leverages the work that 
Mandy did for modular jars [1] and adds the functionality to validate and 
install a signed modular jar file. The signed jar's code signers and optional 
timestamp information are validated and stored in the module library and 
permissions are granted based on the configured security policy.

Please note that signatures on a pre-modularized signed jar must be removed and 
regenerated after it is repackaged as a modular jar. This is because existing 
signatures will become invalid after the module-info class is added to the jar file.

Webrev at: 
http://cr.openjdk.java.net/~mullan/jigsaw/webrevs/signed-modular-jars/webrev.00/

--Sean

[1] http://mail.openjdk.java.net/pipermail/jigsaw-dev/2011-April/001230.html