Update version to 1.6.99

Set the stage for 1.7 development

Change-Id: I9f65d5c4ca5ad6c40e1462d73e3db13e4b13ac02
Signed-off-by: Anas Nashif <anas.nashif@intel.com>

Makefile

@@ -1,5 +1,5 @@
 VERSION_MAJOR 	   = 1
-VERSION_MINOR 	   = 5
+VERSION_MINOR 	   = 6
 PATCHLEVEL 	   = 99
 VERSION_RESERVED   = 0
 EXTRAVERSION       =