Improve build instructions

[jefftrull]

A naive user will have trouble building this library when they follow the directions in README.md. With a freshly cloned repo and Ubuntu 12.10, the build directions as given produce this result:

error: Unable to find file or target named
error: '/boost//headers'
error: referred from project at
error: '.'

It may be that there need to be different/more explicit directions, or it may be that we are assuming people are using a downloaded version of Boost they have built somewhere (instead of their system installation), or both.

[mightypenguin]

The build setup also does not support Red Hat's (and I assume most distros') installation of Boost packages system wide. It expects everyone to be using a tar ball.

e.g.
/usr/include/boot
/usr/lib64/boost