NotFound
Fixes#8375
When a Lambda or an associated Event Source Mapping has been removed via
the AWS Console, Terraform throws an error similar to the following:
```
Error refreshing state: 1 error(s) occurred:
* aws_lambda_event_source_mapping.dmp_enrichment_event_source_mapping:
* ResourceNotFoundException: The resource you requested does not exist.
status code: 404, request id: a17c641d-6868-11e6-accf-3d0ea71934fa
```
the resource should be refreshed from the state when this happens so
that subsequent plans show it needs to be recreated
```
% make testacc TEST=./builtin/providers/aws TESTARGS='-run=TestAccAWSLambdaEventSourceMapping_'
==> Checking that code complies with gofmt requirements...
/Users/stacko/Code/go/bin/stringer
go generate $(go list ./... | grep -v /terraform/vendor/)
2016/08/22 16:15:54 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/aws -v
-run=TestAccAWSLambdaEventSourceMapping_ -timeout 120m
=== RUN TestAccAWSLambdaEventSourceMapping_basic
--- PASS: TestAccAWSLambdaEventSourceMapping_basic (120.81s)
=== RUN TestAccAWSLambdaEventSourceMapping_disappears
--- PASS: TestAccAWSLambdaEventSourceMapping_disappears (104.08s)
PASS
ok github.com/hashicorp/terraform/builtin/providers/aws 224.914s
```