Include docs in the built packages

Seems like people would like the docs included
in the package output, so ensure we pick them
up.

Fixes issue #379

MANIFEST.in

@@ -9,4 +9,5 @@ exclude Makefile
 exclude run_failure.py
 recursive-include kazoo *
 recursive-exclude sw *
+recursive-include docs *
 global-exclude *pyc *pyo