Rename license file and add AUTHORS

AUTHORS

+Jan Frederik Engels <engels+git@dkrz.de>
+Thomas Jahns <jahns@dkrz.de>
+Luis Kornblueh <luis.kornblueh@mpimet.mpg.de>
+Sergey Kosukhin <sergey.kosukhin@mpimet.mpg.de>
+Ralf Mueller <ralf.mueller@dkrz.de>
+Florian Prill <florian.prill@dwd.de>
+Rahul Sinha <rahul.sinha@mpimet.mpg.de>
+Michael Weimer <michael.weimer@kit.edu>
+Karl-Hermann Wieners <karl-hermann.wieners@mpimet.mpg.de>
+Christian Zoller <zoller@informatik.uni-hamburg.de>
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