.travis.yml: Add exclude branch 'sils/*'
.travis.yml: Add exclude branch 'sils/*'

Turns off the travis build for branch
'sils/*' to reduce the unneeded delays.

Closes https://github.com/coala/coala/issues/3516

meetmangukiya/coala,kartikeys98/coala,ayushin78/coala,damngamerz/coala,damngamerz/coala,RJ722/coala,sagark123/coala,arjunsinghy96/coala,netman92/coala,refeed/coala,CruiseDevice/coala,nemaniarjun/coala,Nosferatul/coala,arjunsinghy96/coala,coala-analyzer/coala,yashtrivedi96/coala,shreyans800755/coala,NiklasMM/coala,incorrectusername/coala,arjunsinghy96/coala,Balaji2198/coala,nemaniarjun/coala,sagark123/coala,impmihai/coala,kartikeys98/coala,JohnS-01/coala,arush0311/coala,aptrishu/coala,coala/coala,arush0311/coala,coala-analyzer/coala,karansingh1559/coala,rimacone/testing2,yashLadha/coala,CruiseDevice/coala,refeed/coala,sagark123/coala,Asalle/coala,Nosferatul/coala,Balaji2198/coala,arush0311/coala,Shade5/coala,JohnS-01/coala,yashLadha/coala,Shade5/coala,Nosferatul/coala,incorrectusername/coala,jayvdb/coala,coala/coala,karansingh1559/coala,netman92/coala,Shade5/coala,Asalle/coala,NiklasMM/coala,RJ722/coala,shreyans800755/coala,ayushin78/coala,Asnelchristian/coala,SanketDG/coala,meetmangukiya/coala,karansingh1559/coala,MariosPanag/coala,Asnelchristian/coala,coala-analyzer/coala,nemaniarjun/coala,jayvdb/coala,SanketDG/coala,shreyans800755/coala,yashLadha/coala,CruiseDevice/coala,MariosPanag/coala,yashtrivedi96/coala,meetmangukiya/coala,SanketDG/coala,incorrectusername/coala,aptrishu/coala,ayushin78/coala,MariosPanag/coala,impmihai/coala,NiklasMM/coala,Asnelchristian/coala,rimacone/testing2,yashtrivedi96/coala,aptrishu/coala,RJ722/coala,Balaji2198/coala,netman92/coala,Asalle/coala,rimacone/testing2,damngamerz/coala,refeed/coala,impmihai/coala,kartikeys98/coala,jayvdb/coala,JohnS-01/coala,coala/coala