Add license

LICENSE

+All rights reserved.
+
+This code is under development and not yet released to the public.
+Until it is released, the code is under the copyright of ETH Zurich and
+the University of Bologna, and may contain confidential and/or unpublished
+work. Any reuse/redistribution is strictly forbidden without written
+permission from ETH Zurich.
+Bug fixes and contributions will eventually be released under the
+SolderPad open hardware license in the context of the PULP platform
+(http://www.pulp-platform.org), under the copyright of ETH Zurich and the
+University of Bologna.
\ No newline at end of file