Update bruteforcesysent for 10.9

This PR contains a couple of combined changes:

* Modify the README to have the neat ASCII art, and make it a little more "githuby"

* Update `sysent.h` to include new OSX10.9 sysent structure when it is being built against OSX 10.9

* Update Xcode project to new "recommended" settings, to get rid of annoying compiler warning.