Changing the way we mattermost handles URLs. team.domain.com becomes domain.com/team.

Renaming team.Name to team.DisplayName and team.Domain to team.Name.
So: team.Name -> url safe name. team.DisplayName -> nice name for users

api/templates/post_subject.html

@@ -1 +1 @@
-{{define "post_subject"}}[{{.Props.TeamName}} {{.SiteName}}] {{.Props.SubjectText}} for {{.Props.Month}} {{.Props.Day}}, {{.Props.Year}}{{end}}
+{{define "post_subject"}}[{{.Props.TeamDisplayName}} {{.SiteName}}] {{.Props.SubjectText}} for {{.Props.Month}} {{.Props.Day}}, {{.Props.Year}}{{end}}