SETI-1023: extract filenames after push event correctly
SETI-1023: extract filenames after push event correctly

It works like this:

  > gh = github3.login('mytoken')
  > repo = gh.repository('gooddata', 'ci-infra')
  > [f['filename'] for f in repo.compare_commits('c403edb', '4d73941').files]
  [u'.jenkins-jobs.ini.tpl', u'jenkins/jobs/templates/util-jobs.yaml']

gooddata/zuul,gooddata/zuul,gooddata/zuul,gooddata/zuul,gooddata/zuul