[Raven-devel] gem tasks

[Matthew Foemmel]

I've just checked in some changes to the gem create/install tasks:
    * They've been moved into their own files in the tasks directory
    * The install task no longer inherits from the create task - instead, you can have an install task depend on a create task, and the name of the gem will be passed into the install task via the channel "gem_files"
    * I've renamed the "gem_wrap" method to just "gem" (to make it similar to the "jar" method).

The code currently doesn't run using JRuby 0.9.2, unfortunately, but does work with the latest from JRuby trunk. Should we update the the JRuby vendor branch with a snapshot from trunk?