restore original Sandia copyright

I mistakenly changed the copyright when I forked the Sandia-Labs/PVLIB_Python project to UARENForecasting/PVLIB_Python. Then, the modified license was mistakenly applied to pvlib/pvlib-python during the merging of the above projects. As required by the license, the copyright is Sandia's.

Author: wholmgren

LICENSE

@@ -1,7 +1,4 @@
-Some components copyright (c) 2014, The University of Arizona
-All rights reserved. UA licensing details to be worked out later - danger!
-
-Some components copyright (c) 2013, Sandia National Labs
+Copyright (c) 2013, Sandia National Labs
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without modification,