Add `:scalastyle_integration` test to `:integration` test target
Add `:scalastyle_integration` test to `:integration` test target

This target seems to have been left out unintentionally so it's not currently
being exercised by the integration tests.

Testing Done:
I'm relying on travis to test this since the only way to exercise this code change is to run the `:integration` test target.

Travis link: https://travis-ci.org/pantsbuild/pants/builds/80542329

Bugs closed: 2204

Reviewed at https://rbcommons.com/s/twitter/r/2830/

dturner-tw/pants,dbentley/pants,pantsbuild/pants,ericzundel/pants,lahosken/pants,wisechengyi/pants,ity/pants,UnrememberMe/pants,kwlzn/pants,slyphon/pants,baroquebobcat/pants,kwlzn/pants,foursquare/pants,benjyw/pants,qma/pants,megaserg/pants,peiyuwang/pants,fkorotkov/pants,twitter/pants,jessrosenfield/pants,jsirois/pants,foursquare/pants,tdyas/pants,landism/pants,pantsbuild/pants,UnrememberMe/pants,peiyuwang/pants,dbentley/pants,peiyuwang/pants,cevaris/pants,kwlzn/pants,tdyas/pants,dturner-tw/pants,baroquebobcat/pants,twitter/pants,pombredanne/pants,foursquare/pants,lahosken/pants,qma/pants,foursquare/pants,wisechengyi/pants,kslundberg/pants,foursquare/pants,ity/pants,foursquare/pants,megaserg/pants,benjyw/pants,cevaris/pants,kwlzn/pants,gmalmquist/pants,sameerparekh/pants,15Dkatz/pants,landism/pants,wisechengyi/pants,manasapte/pants,slyphon/pants,dturner-tw/pants,ericzundel/pants,foursquare/pants,fkorotkov/pants,kwlzn/pants,qma/pants,fkorotkov/pants,dturner-tw/pants,wisechengyi/pants,sameerparekh/pants,jtrobec/pants,twitter/pants,gmalmquist/pants,sameerparekh/pants,UnrememberMe/pants,wisechengyi/pants,baroquebobcat/pants,baroquebobcat/pants,jtrobec/pants,baroquebobcat/pants,lahosken/pants,dbentley/pants,sameerparekh/pants,pantsbuild/pants,jessrosenfield/pants,UnrememberMe/pants,dbentley/pants,fkorotkov/pants,jsirois/pants,15Dkatz/pants,peiyuwang/pants,jtrobec/pants,cevaris/pants,gmalmquist/pants,mateor/pants,pombredanne/pants,ity/pants,kslundberg/pants,dturner-tw/pants,wisechengyi/pants,mateor/pants,dbentley/pants,landism/pants,qma/pants,twitter/pants,mateor/pants,cevaris/pants,benjyw/pants,ity/pants,manasapte/pants,pantsbuild/pants,ericzundel/pants,pantsbuild/pants,pombredanne/pants,megaserg/pants,jessrosenfield/pants,landism/pants,landism/pants,15Dkatz/pants,baroquebobcat/pants,manasapte/pants,manasapte/pants,foursquare/pants,benjyw/pants,slyphon/pants,qma/pants,kwlzn/pants,wisechengyi/pants,twitter/pants,tdyas/pants,ericzundel/pants,twitter/pants,peiyuwang/pants,15Dkatz/pants,pombredanne/pants,landism/pants,cevaris/pants,ity/pants,twitter/pants,kslundberg/pants,15Dkatz/pants,mateor/pants,fkorotkov/pants,kslundberg/pants,fkorotkov/pants,landism/pants,tdyas/pants,manasapte/pants,UnrememberMe/pants,megaserg/pants,manasapte/pants,landism/pants,twitter/pants,jtrobec/pants,gmalmquist/pants,qma/pants,pombredanne/pants,lahosken/pants,manasapte/pants,slyphon/pants,pantsbuild/pants,tdyas/pants,jtrobec/pants,jtrobec/pants,pantsbuild/pants,benjyw/pants,peiyuwang/pants,jessrosenfield/pants,UnrememberMe/pants,kslundberg/pants,ericzundel/pants,UnrememberMe/pants,slyphon/pants,ity/pants,ericzundel/pants,slyphon/pants,kslundberg/pants,slyphon/pants,jtrobec/pants,lahosken/pants,mateor/pants,sameerparekh/pants,mateor/pants,megaserg/pants,sameerparekh/pants,baroquebobcat/pants,UnrememberMe/pants,sameerparekh/pants,cevaris/pants,gmalmquist/pants,15Dkatz/pants,tdyas/pants,baroquebobcat/pants,kwlzn/pants,peiyuwang/pants,jessrosenfield/pants,mateor/pants,tdyas/pants,lahosken/pants,dturner-tw/pants,benjyw/pants,15Dkatz/pants,pombredanne/pants,dturner-tw/pants,dbentley/pants,jessrosenfield/pants,pombredanne/pants,foursquare/pants,fkorotkov/pants,gmalmquist/pants,15Dkatz/pants,baroquebobcat/pants,wisechengyi/pants,kslundberg/pants,lahosken/pants,lahosken/pants,ericzundel/pants,qma/pants,mateor/pants,fkorotkov/pants,tdyas/pants,wisechengyi/pants,tdyas/pants,megaserg/pants,jessrosenfield/pants,peiyuwang/pants,twitter/pants,cevaris/pants,megaserg/pants,dbentley/pants,gmalmquist/pants,ericzundel/pants,ity/pants,UnrememberMe/pants,benjyw/pants,jsirois/pants