appveyor.yml: Use builtin download command
appveyor.yml: Use builtin download command

Use ``DownloadFile`` instead of curl. The latter seems to
be absent for some reason (even though their docs claim
otherwise).

Fixes https://github.com/coala/coala/issues/3961

Shade5/coala,aptrishu/coala,JohnS-01/coala,Nosferatul/coala,nemaniarjun/coala,netman92/coala,nemaniarjun/coala,MariosPanag/coala,ayushin78/coala,kartikeys98/coala,RJ722/coala,damngamerz/coala,coala/coala,rimacone/testing2,RJ722/coala,rimacone/testing2,arjunsinghy96/coala,rimacone/testing2,CruiseDevice/coala,Balaji2198/coala,coala-analyzer/coala,yashLadha/coala,karansingh1559/coala,netman92/coala,shreyans800755/coala,Asalle/coala,Asnelchristian/coala,karansingh1559/coala,jayvdb/coala,arush0311/coala,Asalle/coala,RJ722/coala,SanketDG/coala,Shade5/coala,SanketDG/coala,Nosferatul/coala,incorrectusername/coala,ayushin78/coala,coala-analyzer/coala,JohnS-01/coala,CruiseDevice/coala,refeed/coala,damngamerz/coala,karansingh1559/coala,jayvdb/coala,yashLadha/coala,coala/coala,shreyans800755/coala,coala-analyzer/coala,netman92/coala,Asnelchristian/coala,Balaji2198/coala,SanketDG/coala,Asnelchristian/coala,damngamerz/coala,jayvdb/coala,aptrishu/coala,aptrishu/coala,Asalle/coala,MariosPanag/coala,arush0311/coala,nemaniarjun/coala,refeed/coala,kartikeys98/coala,Shade5/coala,ayushin78/coala,MariosPanag/coala,Nosferatul/coala,yashLadha/coala,incorrectusername/coala,Balaji2198/coala,JohnS-01/coala,coala/coala,arush0311/coala,arjunsinghy96/coala,arjunsinghy96/coala,kartikeys98/coala,refeed/coala,shreyans800755/coala,incorrectusername/coala,CruiseDevice/coala