Update README and add contrib dir

contrib/ethernet/CMakeLists.txt

@@ -0,0 +1,28 @@
+check_include_file_cxx(stdint.h HAVE_STDINT_H)
+if(HAVE_STDINT_H)
+    add_definitions(-DHAVE_STDINT_H)
+endif()
+
+set(examples_as_tests_sources)
+if(${ENABLE_EXAMPLES})
+    set(examples_as_tests_sources
+        #test/ethernet-examples-test-suite.cc
+        )
+endif()
+
+build_lib(
+    LIBNAME ethernet
+    SOURCE_FILES model/ethernet-channel.cc
+                 model/ethernet-header2.cc
+                 model/ethernet-net-device.cc
+                 model/switch-net-device.cc
+                 model/switch-channel.cc
+    HEADER_FILES model/ethernet-channel.h
+                 model/ethernet-header2.h
+                 model/ethernet-net-device.h
+                 model/switch-net-device.h
+                 model/switch-channel.h
+    LIBRARIES_TO_LINK ${libcore}
+    TEST_SOURCES test/ethernet-test-suite.cc
+                 ${examples_as_tests_sources}
+)