Add test for allowed team name of slack.
Use allowed slack team name.
Merge branch 'slack_team_name' into 'master'

Slack team name

Fixes a problem in slack team name with hyphens.

https://gitlab.com/gitlab-org/gitlab-ce/issues/701

See merge request !1204
Merge branch 'master' of github.com:gitlabhq/gitlabhq