Install bus.h

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 39bf834..74bd3c5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -207,6 +207,7 @@
 install (FILES src/fanin.h DESTINATION include/nanomsg)
 install (FILES src/fanout.h DESTINATION include/nanomsg)
 install (FILES src/survey.h DESTINATION include/nanomsg)
+install (FILES src/bus.h DESTINATION include/nanomsg)
 
 #  Packaging.