Fixes: #12506
When a replication_task cdc_start_time was specified as an int, it was
causing a panic as the conversion to a Unix timestampe was expecting a
string
```
% make testacc TEST=./builtin/providers/aws TESTARGS='-run=TestAccAwsDmsReplicationTaskBasic'
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2017/03/08 22:55:29 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/aws -v -run=TestAccAwsDmsReplicationTaskBasic -timeout 120m
=== RUN TestAccAwsDmsReplicationTaskBasic
--- PASS: TestAccAwsDmsReplicationTaskBasic (1089.77s)
PASS
ok github.com/hashicorp/terraform/builtin/providers/aws 1089.802s
```
* Add aws dms vendoring
* Add aws dms endpoint resource
* Add aws dms replication instance resource
* Add aws dms replication subnet group resource
* Add aws dms replication task resource
* Fix aws dms resource go vet errors
* Review fixes: Add id validators for all resources. Add validator for endpoint engine_name.
* Add aws dms resources to importability list
* Review fixes: Add aws dms iam role dependencies to test cases
* Review fixes: Adjustments for handling input values
* Add aws dms replication subnet group tagging
* Fix aws dms subnet group doesn't use standard error for resource not found
* Missed update of aws dms vendored version
* Add aws dms certificate resource
* Update aws dms resources to force new for immutable attributes
* Fix tests failing on subnet deletion by adding explicit dependencies. Combine import tests with basic tests to cut down runtime.
Paul Stack