Update NEWS for upcoming 3.0 release

Set a release date of 01 Sep 2015.

NEWS

@@ -6,7 +6,7 @@ Copyright (C) 2000-2015  Stephane Fillod, and others
 Please send Hamlib bug reports to hamlib-developer@lists.sourceforge.net
 
 Version 3.0
-	2015-??-??
+	2015-09-01
 	* Kill RPC backends and rpc.rigd/rpc.rotd
 	* Remove -e|--end-marker option from rigctld and rotctld
 	* Build system updates--remove obsolete macros, autogen.sh now
@@ -54,6 +54,8 @@ Version 3.0
 	* New IC-M700PRO, IC-M710, IC-M802.
 	* New Icom ID-5100 model.
 	* New rotor, cnctrk by KI4SBL
+	* Many backend fixes and updates from many contributors (see Git
+	  log for complete details).
 
 Version 1.2.15.3
 	2012-11-01