[AIRFLOW-2737] Restore original license header
[AIRFLOW-2737] Restore original license header

Closes #3591 from seelmann/AIRFLOW-2737-restore-
original-license-header

apache/incubator-airflow,Fokko/incubator-airflow,gtoonstra/airflow,subodhchhabra/airflow,wooga/airflow,apache/airflow,danielvdende/incubator-airflow,artwr/airflow,apache/airflow,artwr/airflow,nathanielvarona/airflow,r39132/airflow,wileeam/airflow,apache/airflow,sergiohgz/incubator-airflow,cfei18/incubator-airflow,fenglu-g/incubator-airflow,mtagle/airflow,danielvdende/incubator-airflow,adamhaney/airflow,adamhaney/airflow,jgao54/airflow,Acehaidrey/incubator-airflow,sekikn/incubator-airflow,cfei18/incubator-airflow,apache/incubator-airflow,bolkedebruin/airflow,Acehaidrey/incubator-airflow,wileeam/airflow,nathanielvarona/airflow,bolkedebruin/airflow,malmiron/incubator-airflow,akosel/incubator-airflow,criccomini/airflow,airbnb/airflow,sid88in/incubator-airflow,edgarRd/incubator-airflow,mtagle/airflow,sekikn/incubator-airflow,DinoCow/airflow,spektom/incubator-airflow,r39132/airflow,nathanielvarona/airflow,mtagle/airflow,jgao54/airflow,nathanielvarona/airflow,sekikn/incubator-airflow,bolkedebruin/airflow,airbnb/airflow,wooga/airflow,subodhchhabra/airflow,sid88in/incubator-airflow,gtoonstra/airflow,mistercrunch/airflow,malmiron/incubator-airflow,edgarRd/incubator-airflow,andyxhadji/incubator-airflow,apache/airflow,jgao54/airflow,edgarRd/incubator-airflow,cfei18/incubator-airflow,criccomini/airflow,apache/incubator-airflow,akosel/incubator-airflow,wooga/airflow,bolkedebruin/airflow,edgarRd/incubator-airflow,danielvdende/incubator-airflow,gtoonstra/airflow,lyft/incubator-airflow,spektom/incubator-airflow,criccomini/airflow,dhuang/incubator-airflow,r39132/airflow,artwr/airflow,sid88in/incubator-airflow,spektom/incubator-airflow,sekikn/incubator-airflow,mtagle/airflow,mistercrunch/airflow,akosel/incubator-airflow,wileeam/airflow,apache/airflow,gtoonstra/airflow,sergiohgz/incubator-airflow,malmiron/incubator-airflow,r39132/airflow,Acehaidrey/incubator-airflow,dhuang/incubator-airflow,airbnb/airflow,nathanielvarona/airflow,Fokko/incubator-airflow,nathanielvarona/airflow,lyft/incubator-airflow,bolkedebruin/airflow,mistercrunch/airflow,cfei18/incubator-airflow,wileeam/airflow,andyxhadji/incubator-airflow,andyxhadji/incubator-airflow,apache/incubator-airflow,DinoCow/airflow,subodhchhabra/airflow,wooga/airflow,criccomini/airflow,fenglu-g/incubator-airflow,sergiohgz/incubator-airflow,cfei18/incubator-airflow,apache/airflow,lyft/incubator-airflow,DinoCow/airflow,mrkm4ntr/incubator-airflow,dhuang/incubator-airflow,Acehaidrey/incubator-airflow,cfei18/incubator-airflow,danielvdende/incubator-airflow,mrkm4ntr/incubator-airflow,sid88in/incubator-airflow,dhuang/incubator-airflow,akosel/incubator-airflow,Fokko/incubator-airflow,andyxhadji/incubator-airflow,Acehaidrey/incubator-airflow,mistercrunch/airflow,mrkm4ntr/incubator-airflow,fenglu-g/incubator-airflow,mrkm4ntr/incubator-airflow,danielvdende/incubator-airflow,malmiron/incubator-airflow,spektom/incubator-airflow,DinoCow/airflow,artwr/airflow,Fokko/incubator-airflow,adamhaney/airflow,Acehaidrey/incubator-airflow,adamhaney/airflow,subodhchhabra/airflow,danielvdende/incubator-airflow,jgao54/airflow,airbnb/airflow,sergiohgz/incubator-airflow,fenglu-g/incubator-airflow,lyft/incubator-airflow