Refactored BACnetShedLevel encoding, decoding, and printing into separate file. Added unit testing. (#1187)

* Refactored BACnetShedLevel encoding, decoding, and printing into separate file.  Added unit testing.

* Added API to load control object for shed-level, start-time, duty-window, full-duty-baseline, and enable.

* Fixed bacapp sprintf for shed level and host-n-port found in scan build.

ports/at91sam7s/CMakeLists.txt

@@ -168,6 +168,7 @@ set(BACNET_PROJECT_SOURCE
     ${LIBRARY_BACNET_CORE}/reject.c
     ${LIBRARY_BACNET_CORE}/rp.c
     ${LIBRARY_BACNET_CORE}/rpm.c
+    ${LIBRARY_BACNET_CORE}/shed_level.c
     ${LIBRARY_BACNET_CORE}/timer_value.c
     ${LIBRARY_BACNET_CORE}/timestamp.c
     ${LIBRARY_BACNET_CORE}/weeklyschedule.c