[boost] Smoke tests

I'm calling the rapid turnaround tests "Smoke Tests". A section has been added to the testing doc page explaining them, with links to results; see: http://beta.boost.org/development/testing.html The Win32 and Ubuntu tests are currently checking for svn updates every 15 minutes. These tests are run on fast modern machines, so the tests usually take less than 5 minutes. Of course it will take longer if a header changes that lots of libraries depend on. I've also going to try to add Mac OS-X to the mix, but that machine is old and slow so cycle times are likely to be much longer. It will get added to the web page as soon as it is cycling regularly. Enjoy, --Beman