Refactor to extract shell quoting into utility function.
Refactor to extract shell quoting into utility function.

zhouyuan/teuthology,yghannam/teuthology,robbat2/teuthology,dmick/teuthology,ceph/teuthology,dmick/teuthology,SUSE/teuthology,ktdreyer/teuthology,caibo2014/teuthology,t-miyamae/teuthology,ktdreyer/teuthology,robbat2/teuthology,zhouyuan/teuthology,ivotron/teuthology,dmick/teuthology,caibo2014/teuthology,dreamhost/teuthology,SUSE/teuthology,tchaikov/teuthology,SUSE/teuthology,michaelsevilla/teuthology,ivotron/teuthology,tchaikov/teuthology,michaelsevilla/teuthology,dreamhost/teuthology,ceph/teuthology,t-miyamae/teuthology,yghannam/teuthology