Correctly kill the server started with ujs test
Correctly kill the server started with ujs test

`Kernel.#spawn` execute command via the shell if contains shell
metacharacters in the command.
In that case, return value of `spawn` is pid of the shell, not the server.
Therefore, just killing the pid will leave the process of server.

In order to correctly kill the server, send a signal to the process
group, not the process.

flanger001/rails,illacceptanything/illacceptanything,repinel/rails,iainbeeston/rails,gauravtiwari/rails,rails/rails,brchristian/rails,fabianoleittes/rails,aditya-kapoor/rails,georgeclaghorn/rails,BlakeWilliams/rails,vipulnsward/rails,Vasfed/rails,eileencodes/rails,MSP-Greg/rails,printercu/rails,utilum/rails,schuetzm/rails,illacceptanything/illacceptanything,fabianoleittes/rails,assain/rails,schuetzm/rails,pvalena/rails,brchristian/rails,utilum/rails,aditya-kapoor/rails,illacceptanything/illacceptanything,rafaelfranca/omg-rails,travisofthenorth/rails,tgxworld/rails,prathamesh-sonpatki/rails,tjschuck/rails,assain/rails,Vasfed/rails,Vasfed/rails,untidy-hair/rails,illacceptanything/illacceptanything,yahonda/rails,illacceptanything/illacceptanything,schuetzm/rails,MSP-Greg/rails,yalab/rails,fabianoleittes/rails,mohitnatoo/rails,repinel/rails,bogdanvlviv/rails,EmmaB/rails-1,Envek/rails,gauravtiwari/rails,rafaelfranca/omg-rails,kddeisz/rails,yawboakye/rails,rails/rails,starknx/rails,deraru/rails,yasslab/railsguides.jp,iainbeeston/rails,gfvcastro/rails,flanger001/rails,illacceptanything/illacceptanything,shioyama/rails,illacceptanything/illacceptanything,Edouard-chin/rails,georgeclaghorn/rails,Erol/rails,Vasfed/rails,lcreid/rails,flanger001/rails,Stellenticket/rails,fabianoleittes/rails,yhirano55/rails,baerjam/rails,illacceptanything/illacceptanything,Erol/rails,repinel/rails,illacceptanything/illacceptanything,joonyou/rails,kddeisz/rails,tgxworld/rails,bogdanvlviv/rails,lcreid/rails,brchristian/rails,Erol/rails,Stellenticket/rails,illacceptanything/illacceptanything,yawboakye/rails,esparta/rails,kmcphillips/rails,Edouard-chin/rails,printercu/rails,tgxworld/rails,starknx/rails,illacceptanything/illacceptanything,Erol/rails,printercu/rails,kmcphillips/rails,prathamesh-sonpatki/rails,betesh/rails,kmcphillips/rails,arunagw/rails,tjschuck/rails,schuetzm/rails,untidy-hair/rails,pvalena/rails,jeremy/rails,deraru/rails,yahonda/rails,illacceptanything/illacceptanything,palkan/rails,lcreid/rails,kddeisz/rails,Stellenticket/rails,shioyama/rails,Stellenticket/rails,mohitnatoo/rails,illacceptanything/illacceptanything,Edouard-chin/rails,utilum/rails,eileencodes/rails,georgeclaghorn/rails,illacceptanything/illacceptanything,EmmaB/rails-1,joonyou/rails,notapatch/rails,yalab/rails,yasslab/railsguides.jp,MSP-Greg/rails,mechanicles/rails,assain/rails,odedniv/rails,pvalena/rails,mechanicles/rails,travisofthenorth/rails,starknx/rails,kddeisz/rails,MSP-Greg/rails,iainbeeston/rails,notapatch/rails,yawboakye/rails,BlakeWilliams/rails,rafaelfranca/omg-rails,yasslab/railsguides.jp,rails/rails,shioyama/rails,jeremy/rails,tjschuck/rails,utilum/rails,gauravtiwari/rails,yhirano55/rails,bogdanvlviv/rails,BlakeWilliams/rails,betesh/rails,yawboakye/rails,jeremy/rails,tgxworld/rails,georgeclaghorn/rails,joonyou/rails,esparta/rails,Edouard-chin/rails,travisofthenorth/rails,tjschuck/rails,deraru/rails,gfvcastro/rails,arunagw/rails,palkan/rails,vipulnsward/rails,odedniv/rails,aditya-kapoor/rails,gfvcastro/rails,EmmaB/rails-1,mohitnatoo/rails,assain/rails,notapatch/rails,printercu/rails,Envek/rails,shioyama/rails,yahonda/rails,jeremy/rails,baerjam/rails,eileencodes/rails,betesh/rails,arunagw/rails,eileencodes/rails,bogdanvlviv/rails,odedniv/rails,yasslab/railsguides.jp,untidy-hair/rails,Envek/rails,joonyou/rails,repinel/rails,yalab/rails,aditya-kapoor/rails,mohitnatoo/rails,betesh/rails,illacceptanything/illacceptanything,gfvcastro/rails,kmcphillips/rails,arunagw/rails,BlakeWilliams/rails,prathamesh-sonpatki/rails,iainbeeston/rails,mechanicles/rails,esparta/rails,yalab/rails,yhirano55/rails,esparta/rails,baerjam/rails,palkan/rails,untidy-hair/rails,travisofthenorth/rails,flanger001/rails,yhirano55/rails,yahonda/rails,vipulnsward/rails,deraru/rails,notapatch/rails,vipulnsward/rails,Envek/rails,baerjam/rails,prathamesh-sonpatki/rails,lcreid/rails,rails/rails,mechanicles/rails,pvalena/rails,palkan/rails