[AIRFLOW-1637] Fix Travis CI build status link
[AIRFLOW-1637] Fix Travis CI build status link

In the readme it is linking
https://travis-ci.org/apache/incubator-airflow.svg
instead of
https://travis-ci.org/apache/incubator-
airflow.svg?branch=master

So this is showing the build status for the latest
build instead
of the master branch

Closes #2627 from dalupus/airflow-1637

yk5/incubator-airflow,OpringaoDoTurno/airflow,mrkm4ntr/incubator-airflow,gilt/incubator-airflow,andyxhadji/incubator-airflow,airbnb/airflow,Acehaidrey/incubator-airflow,apache/incubator-airflow,wooga/airflow,wooga/airflow,fenglu-g/incubator-airflow,bolkedebruin/airflow,jfantom/incubator-airflow,sekikn/incubator-airflow,danielvdende/incubator-airflow,MortalViews/incubator-airflow,bolkedebruin/airflow,gilt/incubator-airflow,jhsenjaliya/incubator-airflow,DinoCow/airflow,sergiohgz/incubator-airflow,mistercrunch/airflow,dhuang/incubator-airflow,Tagar/incubator-airflow,lyft/incubator-airflow,subodhchhabra/airflow,spektom/incubator-airflow,mrkm4ntr/incubator-airflow,cjqian/incubator-airflow,airbnb/airflow,artwr/airflow,apache/airflow,janczak10/incubator-airflow,fenglu-g/incubator-airflow,yati-sagade/incubator-airflow,DinoCow/airflow,mistercrunch/airflow,wolfier/incubator-airflow,MortalViews/incubator-airflow,gtoonstra/airflow,criccomini/airflow,nathanielvarona/airflow,apache/incubator-airflow,Tagar/incubator-airflow,sergiohgz/incubator-airflow,Acehaidrey/incubator-airflow,r39132/airflow,wndhydrnt/airflow,wileeam/airflow,spektom/incubator-airflow,lxneng/incubator-airflow,owlabs/incubator-airflow,Acehaidrey/incubator-airflow,spektom/incubator-airflow,danielvdende/incubator-airflow,Tagar/incubator-airflow,zack3241/incubator-airflow,gilt/incubator-airflow,mtagle/airflow,skudriashev/incubator-airflow,mrares/incubator-airflow,hgrif/incubator-airflow,zack3241/incubator-airflow,r39132/airflow,KL-WLCR/incubator-airflow,dhuang/incubator-airflow,gtoonstra/airflow,lxneng/incubator-airflow,edgarRd/incubator-airflow,jfantom/incubator-airflow,owlabs/incubator-airflow,OpringaoDoTurno/airflow,cfei18/incubator-airflow,CloverHealth/airflow,CloverHealth/airflow,Acehaidrey/incubator-airflow,danielvdende/incubator-airflow,wileeam/airflow,apache/airflow,yati-sagade/incubator-airflow,OpringaoDoTurno/airflow,apache/airflow,MortalViews/incubator-airflow,apache/airflow,akosel/incubator-airflow,ProstoMaxim/incubator-airflow,owlabs/incubator-airflow,apache/incubator-airflow,sekikn/incubator-airflow,cjqian/incubator-airflow,fenglu-g/incubator-airflow,sekikn/incubator-airflow,RealImpactAnalytics/airflow,subodhchhabra/airflow,KL-WLCR/incubator-airflow,MortalViews/incubator-airflow,sergiohgz/incubator-airflow,cfei18/incubator-airflow,mtagle/airflow,lyft/incubator-airflow,edgarRd/incubator-airflow,adamhaney/airflow,danielvdende/incubator-airflow,ProstoMaxim/incubator-airflow,apache/airflow,andyxhadji/incubator-airflow,danielvdende/incubator-airflow,RealImpactAnalytics/airflow,wolfier/incubator-airflow,CloverHealth/airflow,DinoCow/airflow,ProstoMaxim/incubator-airflow,yk5/incubator-airflow,artwr/airflow,ProstoMaxim/incubator-airflow,Acehaidrey/incubator-airflow,nathanielvarona/airflow,lyft/incubator-airflow,wooga/airflow,subodhchhabra/airflow,RealImpactAnalytics/airflow,jgao54/airflow,airbnb/airflow,KL-WLCR/incubator-airflow,akosel/incubator-airflow,wileeam/airflow,sid88in/incubator-airflow,sergiohgz/incubator-airflow,nathanielvarona/airflow,mistercrunch/airflow,jhsenjaliya/incubator-airflow,mtagle/airflow,hgrif/incubator-airflow,adamhaney/airflow,mrares/incubator-airflow,edgarRd/incubator-airflow,sid88in/incubator-airflow,janczak10/incubator-airflow,wileeam/airflow,lxneng/incubator-airflow,KL-WLCR/incubator-airflow,andyxhadji/incubator-airflow,artwr/airflow,criccomini/airflow,nathanielvarona/airflow,andyxhadji/incubator-airflow,mrkm4ntr/incubator-airflow,malmiron/incubator-airflow,wooga/airflow,spektom/incubator-airflow,dhuang/incubator-airflow,danielvdende/incubator-airflow,akosel/incubator-airflow,mrares/incubator-airflow,janczak10/incubator-airflow,edgarRd/incubator-airflow,bolkedebruin/airflow,zack3241/incubator-airflow,skudriashev/incubator-airflow,jgao54/airflow,zack3241/incubator-airflow,malmiron/incubator-airflow,skudriashev/incubator-airflow,fenglu-g/incubator-airflow,jgao54/airflow,mrkm4ntr/incubator-airflow,cfei18/incubator-airflow,jhsenjaliya/incubator-airflow,gilt/incubator-airflow,cjqian/incubator-airflow,bolkedebruin/airflow,apache/airflow,yati-sagade/incubator-airflow,jfantom/incubator-airflow,Fokko/incubator-airflow,cfei18/incubator-airflow,criccomini/airflow,wndhydrnt/airflow,yati-sagade/incubator-airflow,cjqian/incubator-airflow,wndhydrnt/airflow,janczak10/incubator-airflow,cfei18/incubator-airflow,yk5/incubator-airflow,mistercrunch/airflow,yk5/incubator-airflow,Fokko/incubator-airflow,airbnb/airflow,sid88in/incubator-airflow,apache/incubator-airflow,mtagle/airflow,wndhydrnt/airflow,owlabs/incubator-airflow,skudriashev/incubator-airflow,Tagar/incubator-airflow,Fokko/incubator-airflow,adamhaney/airflow,criccomini/airflow,cfei18/incubator-airflow,sekikn/incubator-airflow,r39132/airflow,hgrif/incubator-airflow,hgrif/incubator-airflow,RealImpactAnalytics/airflow,malmiron/incubator-airflow,akosel/incubator-airflow,CloverHealth/airflow,jfantom/incubator-airflow,nathanielvarona/airflow,Acehaidrey/incubator-airflow,wolfier/incubator-airflow,jgao54/airflow,bolkedebruin/airflow,lxneng/incubator-airflow,gtoonstra/airflow,r39132/airflow,jhsenjaliya/incubator-airflow,dhuang/incubator-airflow,adamhaney/airflow,mrares/incubator-airflow,wolfier/incubator-airflow,OpringaoDoTurno/airflow,subodhchhabra/airflow,malmiron/incubator-airflow,artwr/airflow,lyft/incubator-airflow,nathanielvarona/airflow,DinoCow/airflow,gtoonstra/airflow,Fokko/incubator-airflow,sid88in/incubator-airflow