added support for a separate throws indentation configuration

Hi,

This pull request addresses issue #63 (in GitHub).  It also addresses the older sourceforge ticket: http://sourceforge.net/p/checkstyle/feature-requests/294/

It gives you the ability to define a separate indentation for "throws".  It's mostly not my code, but Maikel Steneker's (@maikelsteneker).  Maikel had forked the original checkstyle repo and added support for a separate throws indentation (and then made it available on GitHub).  I found Maikel's repo awhile back and have been using it.  It works great with Maven and Eclipse.

I just added a unit test to what Maikel had already created and set up this branch so that I could submit it as a pull request since checkstyle development is picking up again.  I think this should be an easy merge?

Thanks for looking into it.