Proposal: add an update option to the JAR task def

[Wong Kok Wai <wo...@pacific.net.sg>]

I like to propose adding an update option to the JAR task def. Updating
of jar can be done using the "-u" option. For ANT, we can have either:

<jar action="update|create" .../> (create is the default)

or

<jar update="true" ... /> (false by default)

What do you think?