Add basic license files

LICENSE

+Copyright ©2018, 2019, University of Texas Southwestern Medical Center. All rights reserved.
+Contributors: David C. Trudgian, Wei Guo
+Department: BioHPC, Lyda Hill Department of Bioinformatics
+ 
+This software is licensed under GPL v3.0
+(https://www.gnu.org/licenses/gpl-3.0.en.html)
+  
+For an alternative license, please contact the Office for Technology Development
+at University of Texas Southwestern Medical Center, Dallas, TX
+(TechnologyDevelopment@utsouthwestern.edu)
+