Fix generator integration tests to use verdaccio

Signed-off-by: Simon Stone <sstone1@uk.ibm.com>

packages/composer-tests-integration/features/generator-busnet.feature

@@ -24,7 +24,7 @@ Feature: Business Network Generator
     Scenario: Using the Composer generator, I can install the business network packages
         When I run the following expected pass CLI command
             """
-             npm install --prefix ./my-bus-net
+             npm install --registry http://localhost:4873 --prefix ./my-bus-net
             """
         Then The stdout information should include text matching /added .* packages/