Automatized changes to license and copyright information

These are automatically created changes. They should include

• a LICENSE.txt file, if such a file was not already present
• added copyright headers to all .py, .scala files that did not already had one
• updated copyright headers to all .py, .scala files that attribute copyright to the non existing legal entity NOMAD Developers Group

Please do carefully check the proposed changes and accept the merge if appropriate, or comment to this merge request otherwise.

parser/parser-big-dft/bigdftparser/generic/libxc_codes.py

+# Copyright 2016-2018 Lauri Himanen, Fawzi Mohamed
+# 
+#   Licensed under the Apache License, Version 2.0 (the "License");
+#   you may not use this file except in compliance with the License.
+#   You may obtain a copy of the License at
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0
+# 
+#   Unless required by applicable law or agreed to in writing, software
+#   distributed under the License is distributed on an "AS IS" BASIS,
+#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#   See the License for the specific language governing permissions and
+#   limitations under the License.
+
 LIB_XC_MAPPING = {
     "001": "LDA_X",
     "002": "LDA_C_WIGNER",