Fix all uncompressed artifacts stored as just '.tar'
Fix all uncompressed artifacts stored as just '.tar'

Testing Done:
https://travis-ci.org/pantsbuild/pants/builds/38738752

Reviewed at https://rbcommons.com/s/twitter/r/1197/

mateor/pants,jtrobec/pants,peiyuwang/pants,di0spyr0s/pants,scode/pants,pombredanne/pants,15Dkatz/pants,foursquare/pants,sid-kap/pants,dgomez10/xanon,twitter/pants,dgomez10/xanon,lahosken/pants,UnrememberMe/pants,benjyw/pants,foursquare/pants,jsirois/pants,qma/pants,dturner-tw/pants,peiyuwang/pants,15Dkatz/pants,slyphon/pants,areitz/pants,digwanderlust/pants,peiyuwang/pants,jsirois/pants,dturner-tw/pants,ity/pants,digwanderlust/pants,TansyArron/pants,sid-kap/pants,baroquebobcat/pants,slyphon/pants,UnrememberMe/pants,foursquare/pants,digwanderlust/pants,dbentley/pants,ericzundel/pants,qma/pants,lahosken/pants,mateor/pants,pgroudas/pants,dturner-tw/pants,Gabriel439/pants,kslundberg/pants,dbentley/pants,wisechengyi/pants,TansyArron/pants,landism/pants,mateor/pants,foursquare/pants,landism/pants,laurentgo/pants,manasapte/pants,areitz/pants,cevaris/pants,gmalmquist/pants,kwlzn/pants,fkorotkov/pants,benjyw/pants,benjyw/pants,laurentgo/pants,jtrobec/pants,mateor/pants,kwlzn/pants,tejal29/pants,pombredanne/pants,Gabriel439/pants,fkorotkov/pants,benjyw/pants,megaserg/pants,jessrosenfield/pants,cevaris/pants,manasapte/pants,baroquebobcat/pants,tdyas/pants,digwanderlust/pants,qma/pants,baroquebobcat/pants,kslundberg/pants,tdyas/pants,peiyuwang/pants,dbentley/pants,Gabriel439/pants,tejal29/pants,wisechengyi/pants,sameerparekh/pants,areitz/pants,manasapte/pants,slyphon/pants,foursquare/pants,UnrememberMe/pants,megaserg/pants,cevaris/pants,pgroudas/pants,laurentgo/pants,scode/pants,dbentley/pants,baroquebobcat/pants,pombredanne/pants,dgomez10/xanon,twitter/pants,laurentgo/pants,lahosken/pants,pombredanne/pants,jessrosenfield/pants,pgroudas/pants,megaserg/pants,TansyArron/pants,tdyas/pants,manasapte/pants,square/pants,peiyuwang/pants,Gabriel439/pants,megaserg/pants,areitz/pants,dturner-tw/pants,pgroudas/pants,gmalmquist/pants,dgomez10/xanon,gmalmquist/pants,digwanderlust/pants,jessrosenfield/pants,jtrobec/pants,15Dkatz/pants,digwanderlust/pants,square/pants,pantsbuild/pants,TansyArron/pants,15Dkatz/pants,sameerparekh/pants,gmalmquist/pants,pantsbuild/pants,landism/pants,lahosken/pants,kwlzn/pants,dgomez10/xanon,kslundberg/pants,tejal29/pants,di0spyr0s/pants,slyphon/pants,wisechengyi/pants,sameerparekh/pants,manasapte/pants,wisechengyi/pants,cevaris/pants,tejal29/pants,cevaris/pants,landism/pants,lahosken/pants,gmalmquist/pants,ity/pants,lahosken/pants,ity/pants,lahosken/pants,twitter/pants,ericzundel/pants,wisechengyi/pants,kslundberg/pants,sameerparekh/pants,ericzundel/pants,twitter/pants,fkorotkov/pants,cevaris/pants,dturner-tw/pants,TansyArron/pants,kslundberg/pants,di0spyr0s/pants,tdyas/pants,UnrememberMe/pants,benjyw/pants,ity/pants,di0spyr0s/pants,square/pants,scode/pants,jsirois/pants,TansyArron/pants,ericzundel/pants,benjyw/pants,mateor/pants,gmalmquist/pants,pantsbuild/pants,jessrosenfield/pants,pantsbuild/pants,wisechengyi/pants,tdyas/pants,landism/pants,sid-kap/pants,UnrememberMe/pants,qma/pants,fkorotkov/pants,pantsbuild/pants,15Dkatz/pants,laurentgo/pants,baroquebobcat/pants,square/pants,ericzundel/pants,landism/pants,fkorotkov/pants,Gabriel439/pants,sid-kap/pants,sameerparekh/pants,slyphon/pants,dbentley/pants,ity/pants,mateor/pants,15Dkatz/pants,mateor/pants,scode/pants,fkorotkov/pants,dturner-tw/pants,tdyas/pants,wisechengyi/pants,pombredanne/pants,ity/pants,UnrememberMe/pants,jtrobec/pants,tejal29/pants,twitter/pants,ity/pants,sameerparekh/pants,tdyas/pants,gmalmquist/pants,landism/pants,dturner-tw/pants,laurentgo/pants,dgomez10/xanon,manasapte/pants,qma/pants,peiyuwang/pants,pombredanne/pants,ericzundel/pants,megaserg/pants,manasapte/pants,scode/pants,kslundberg/pants,15Dkatz/pants,jtrobec/pants,sid-kap/pants,wisechengyi/pants,kwlzn/pants,jessrosenfield/pants,dgomez10/xanon,Gabriel439/pants,scode/pants,di0spyr0s/pants,baroquebobcat/pants,scode/pants,areitz/pants,fkorotkov/pants,sid-kap/pants,areitz/pants,lahosken/pants,kwlzn/pants,foursquare/pants,benjyw/pants,pantsbuild/pants,jtrobec/pants,fkorotkov/pants,dgomez10/xanon,pgroudas/pants,UnrememberMe/pants,foursquare/pants,baroquebobcat/pants,sameerparekh/pants,dbentley/pants,15Dkatz/pants,landism/pants,twitter/pants,megaserg/pants,qma/pants,ericzundel/pants,tdyas/pants,foursquare/pants,baroquebobcat/pants,pantsbuild/pants,twitter/pants,ericzundel/pants,di0spyr0s/pants,UnrememberMe/pants,jessrosenfield/pants,slyphon/pants,peiyuwang/pants,megaserg/pants,tdyas/pants,dgomez10/xanon,jessrosenfield/pants,sid-kap/pants,dgomez10/xanon,TansyArron/pants,baroquebobcat/pants,pombredanne/pants,twitter/pants,mateor/pants,twitter/pants,foursquare/pants,pgroudas/pants,dbentley/pants,peiyuwang/pants,UnrememberMe/pants,wisechengyi/pants,jtrobec/pants,kwlzn/pants,dgomez10/xanon,di0spyr0s/pants,areitz/pants,cevaris/pants,qma/pants,Gabriel439/pants,kwlzn/pants,slyphon/pants,kslundberg/pants