Simplify error returns (gosimple)

This fixes:
pkg/api/avatar/avatar.go:261:2: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/log/file.go:102:2: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/metrics/graphitebridge/graphite.go:298:2: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/provisioning/provisioning.go:23:2: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/alert_notification.go:27:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/alert_notification.go:27:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/annotation.go:105:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/annotation.go:105:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/dashboard.go:351:2: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/dashboard.go:435:2: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/dashboard_acl.go:38:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/dashboard_acl.go:38:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/stats.go:22:2: 'if err != nil { return err }; return err' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/team.go:213:2: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/user.go:256:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/user.go:256:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/user.go:274:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/user.go:274:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/user.go:482:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)
pkg/services/sqlstore/user.go:482:3: 'if err != nil { return err }; return nil' can be simplified to 'return err' (S1013)

pkg/services/sqlstore/annotation.go

@@ -102,11 +102,8 @@ func (r *SqlAnnotationRepo) Update(item *annotations.Item) error {
 
 		existing.Tags = item.Tags
 
-		if _, err := sess.Table("annotation").Id(existing.Id).Cols("epoch", "text", "region_id", "tags").Update(existing); err != nil {
-			return err
-		}
-
-		return nil
+		_, err = sess.Table("annotation").Id(existing.Id).Cols("epoch", "text", "region_id", "tags").Update(existing)
+		return err
 	})
 }