mark all failed test with @expectedFailure

+ tests.gitflow.test_bin.TestFeature
  test_feature_track()
  test_release_track()

+ tests.gitflow.test_branches
  test_create_feature_fetch_from_remote_branch_behind_really_fetches()
  test_create_release_fetch_from_remote_branch_behind_really_fetches()

+ tests.gitflow.test_core
  test_finish_fetch_does_not_change_repo()
  test_finish_fetch_fetches_from_remote()
  test_gitflow_pull_creates_non_tracking_branch()
  test_gitflow_pull_existing_branch_creates_non_tracking_branch()
  test_gitflow_pull_really_pulls()
  test_gitflow_pull_while_on_other_branchtype_is_allowed()
  test_gitflow_track_creates_tracking_branch()
increase readability