Merge pull request #803 from adafruit/release-1.6.0

bump up version for release 1.6.0

Author: hathach

platform.txt

@@ -17,7 +17,7 @@
 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
 name=Adafruit nRF52 Boards
-version=1.5.0
+version=1.6.0
 
 # Compile variables
 # -----------------