Migrate functions to app package (#5106)

* Refactor and move session logic into app package

* Refactor email functions into the app package

* Refactor password update into app package

* Migrate user functions to app package

* Move team functions into app package

* Migrate channel functions into app package

* Pass SiteURL through to app functions

* Update based on feedback

store/sql_team_store_test.go

@@ -415,7 +415,7 @@ func TestGetTeamMember(t *testing.T) {
 	if r := <-store.Team().GetMember(m1.TeamId, m1.UserId); r.Err != nil {
 		t.Fatal(r.Err)
 	} else {
-		rm1 := r.Data.(model.TeamMember)
+		rm1 := r.Data.(*model.TeamMember)
 
 		if rm1.TeamId != m1.TeamId {
 			t.Fatal("bad team id")