hs-test: added dry run mode

- DRYRUN=true will set up most containers. Some need to be started
  manually (curl, nginx...). The framework will create a vpp-config
  file with interface configs that will get executed on VPP startup.
- set Ginkgo to use -v instead of -vv when running a single test
- s.Log() now supports formatting
- added 'useEnvVars' parameter to container.Exec

Type: test

Change-Id: Id1da7947a1448ee4b74b86cc4f243442256a5ba8
Signed-off-by: Adrian Villin <avillin@cisco.com>

extras/hs-test/framework_test.go

@@ -33,4 +33,8 @@ func TestHst(t *testing.T) {
 
 	RegisterFailHandler(Fail)
 	RunSpecs(t, "HST")
+	if *DryRun || *IsPersistent {
+		fmt.Println("\033[36m" + "Use 'make cleanup-hst' to remove IP files, " +
+			"namespaces and containers. \nPPID: " + ppid + "\033[0m")
+	}
 }