Feature/write property type check refactor (#182)

* refactor write-property tag check

* modify ports objects to use write-property tag check API

* modify example objects to use write-property tag check API

* Fix object unit test builds

* Fix and run unit ztests via CMake

* Enable unit testing on Travis CI

Co-authored-by: Steve Karg <skarg@users.sourceforge.net>

test/bacnet/basic/object/ao/CMakeLists.txt

@@ -45,7 +45,7 @@ add_executable(${PROJECT_NAME}
 	${SRC_DIR}/bacnet/datetime.c
 	${SRC_DIR}/bacnet/indtext.c
 	${SRC_DIR}/bacnet/lighting.c
-	./stubs.c
+	${SRC_DIR}/bacnet/wp.c
     # Test and test library files
 	./src/main.c
 	${ZTST_DIR}/ztest_mock.c