added SDK 7.1 and 7.0A logic. Needs to be tested on systems with 7.0A installed.  Also fixed some error messages when not finding requested SDK's. Previously would throw an exception
added SDK 7.1 and 7.0A logic. Needs to be tested on systems with 7.0A installed.  Also fixed some error messages when not finding requested SDK's. Previously would throw an exception

andrewyoung1991/scons,andrewyoung1991/scons,timj/scons,timj/scons,timj/scons,andrewyoung1991/scons,andrewyoung1991/scons,timj/scons,andrewyoung1991/scons,andrewyoung1991/scons,timj/scons,andrewyoung1991/scons,andrewyoung1991/scons,timj/scons,timj/scons,timj/scons,timj/scons,andrewyoung1991/scons