Support stemcell name property

Broadcom has started supporting FIPS enabled stemcells whose version
matches the non-FIPS stemcells and without a name specified the FIPS may
unintentionally be used when a deployment might not support FIPS.

To avoid this allow consumers to set a stemcell name property to point
to the expected stemcell name. This allows BOSH to ensure the desired
stemcell is always used and not unintentionally deploying with the wrong
variant.

This commit updates the spec property of the broker job to allow
defining the stemcell.name or stemcells[].name property for a data
service product.

To fully support the name property this depends on changes in the ODB
SDK in pivotal-cf/on-demand-services-sdk#200

jobs/broker/spec

@@ -217,6 +217,9 @@ properties:
       - os: ubuntu
         version: 1234
 
+  service_deployment.stemcell.name:
+    description: stemcell name to use for every job in the service deployment
+
   service_deployment.stemcell.os:
     description: stemcell OS to use for every job in the service deployment
 

jobs/broker/templates/broker.yml.erb

@@ -95,6 +95,7 @@ def prepare_stemcells(service_deployment)
     raise 'Invalid service_deployment config - at least one stemcell must be specified'
   end
 
+  service_deployment['stemcells'].map! { |stemcell| stemcell.compact }
   service_deployment['stemcells'].each do |stemcell|
     validate_stemcell stemcell
   end

spec/broker_config_template_spec.rb

@@ -1143,7 +1143,7 @@
         generate_test_manifest do |yaml|
           yaml['instance_groups'][0]['jobs'][0]['properties']['service_deployment']['stemcells'] = []
           yaml['instance_groups'][0]['jobs'][0]['properties']['service_deployment']['stemcell'] = {
-            'os' => 'ubuntu-trusty', 'version' => 2311
+            'os' => 'ubuntu-trusty', 'version' => "2311", 'name' => 'bosh-warden-boshlite-ubuntu-trusty-go_agent',
           }
           yaml
         end
@@ -1152,7 +1152,7 @@
 
       it 'generates the config with "stemcells"' do
         obj = YAML.load(rendered_template)
-        expect(obj['service_deployment']['stemcells']).to eq([{"os"=>"ubuntu-trusty", "version"=>2311}])
+        expect(obj['service_deployment']['stemcells']).to eq([{"os"=>"ubuntu-trusty", "version"=>"2311", "name" => "bosh-warden-boshlite-ubuntu-trusty-go_agent"}])
         expect(obj['service_deployment']['stemcell']).to be_nil
       end