Problem: libzmq installed during build

There is no need to install libzmq into the system.
Out of source build can be used later to build cppzmq.

Solution: remove install steps and rely more on cmake to handle
directory creation.

demo/CMakeLists.txt

@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.0 FATAL_ERROR)
 
 project(cppzmq-demo CXX)
 
-find_package(cppzmq)
+find_package(cppzmq REQUIRED)
 
 enable_testing()
 add_executable(
@@ -12,9 +12,11 @@ add_executable(
 
 target_link_libraries(
     demo
-    libzmq
+    cppzmq
     )
 
+include_directories(${ZeroMQ_INCLUDE_DIR} ${cppzmq_INCLUDE_DIR})
+
 add_test(
   NAME
     demo