Create Spork::VERSION

Hi Tim, 

Here's a solution for Spork to know its own version number. Could you pull this?

This follows the version example from Carl Lerche and Yehuda Katz in the bundler gem:

  * New file /lib/spork/version.rb that defines Spork::VERSION

  * Update to spork.gemspec to require the version.rb for Spork::VERSION

Note that I bumped the version to rc10 to show how it works-- you may want to alter this. The gem builds fine on my setup.

My contact info is joelparkerhenderson on Gmail and Google Talk if you'd like to ask about it. 

Thanks,
Joel