Added License

LICENSE

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+This source code is being disclosed to you solely for the purpose of your participation in 
+testing Zilliqa. You may view, compile and run the code for that purpose and pursuant to 
+the protocols and algorithms that are programmed into, and intended by, the code. You may 
+not do anything else with the code without express permission from Zilliqa Research Pte. Ltd., 
+including modifying or publishing the code (or any part of it), and developing or forming 
+another public or private blockchain network. This source code is provided ‘as is’ and no 
+warranties are given as to title or non-infringement, merchantability or fitness for purpose 
+and, to the extent permitted by law, all liability for your use of the code is disclaimed. 
+Some programs in this code are governed by the GNU General Public License v3.0 (available at 
+https://www.gnu.org/licenses/gpl-3.0.en.html) (‘GPLv3’). The programs that are governed by 
+GPLv3.0 are those programs that are located in the folders src/depends and tests/depends 
+and which include a reference to GPLv3 in their program files.