add flake8 checks to teuthology
add flake8 checks to teuthology

Signed-off-by: Alfredo Deza <3ae498813ac9b6992b3bb72690656738fc9b4e19@inktank.com>
(cherry picked from commit 27c9eb8f81dc25c7b50bfb77d4d2d4ab4d136fb6)
(cherry picked from commit b390d68ff4b7a648da3f22bd5ae34651d02fd915)

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