api: Add missing GET teams endpoints (#5382)

* api: Add an endpoint to list a particular member of team.

* models: Rename `GetUserTeams()` to `GetUserOrgTeams()` in `org_team` model.

`GetUserTeams()` sounds a bit misnomer since it actually returns
the teams that user belongs to in a given organization rather than
all the teams across all the organization that the user has joined.

* models: Add `GetUserTeams()`.

Returns all the teams that a user belongs to.

* api: Add an endpoint for GET '/user/teams'.

A GET request to this endpoint lists all the teams that a user
belongs to.

routers/api/v1/api.go

@@ -463,6 +463,8 @@ func RegisterRoutes(m *macaron.Macaron) {
 			m.Get("/times", repo.ListMyTrackedTimes)
 
 			m.Get("/subscriptions", user.GetMyWatchedRepos)
+
+			m.Get("/teams", org.ListUserTeams)
 		}, reqToken())
 
 		// Repositories
@@ -652,6 +654,7 @@ func RegisterRoutes(m *macaron.Macaron) {
 			m.Group("/members", func() {
 				m.Get("", org.GetTeamMembers)
 				m.Combo("/:username").
+					Get(org.GetTeamMember).
 					Put(reqOrgOwnership(), org.AddTeamMember).
 					Delete(reqOrgOwnership(), org.RemoveTeamMember)
 			})