Import google_compute_shared_vpc_host_project/google_compute_shared_vpc_service_project resources (hashicorp#1004)

* Import google_compute_shared_vpc_host_project/google_compute_shared_vpc_service_project resources.

* Incorporate testing of resource import into main acceptance tests.

Author: ewbankkit

docs/r/compute_shared_vpc_host_project.html.markdown

@@ -42,3 +42,10 @@ The following arguments are expected:
 
 * `project` - (Required) The ID of the project that will serve as a Shared VPC host project
 
+## Import
+
+Google Compute Engine Shared VPC host project feature can be imported using the `project`, e.g.
+
+```
+$ terraform import google_compute_shared_vpc_host_project.host host-project-id
+```

docs/r/compute_shared_vpc_service_project.html.markdown

@@ -36,3 +36,11 @@ The following arguments are expected:
 * `host_project` - (Required) The ID of a host project to associate.
 
 * `service_project` - (Required) The ID of the project that will serve as a Shared VPC service project.
+
+## Import
+
+Google Compute Engine Shared VPC service project feature can be imported using the `host_project` and `service_project`, e.g.
+
+```
+$ terraform import google_compute_shared_vpc_service_project.service1 host-project-id/service-project-id-1
+```