Remove check for presence of secrets

theatre-envconsul assumes that your app needs secrets when you opt-in by
annotating your service. when it doesn't find the vault: prefix, it errors
as envconsul hangs when provided no secrets. we have now changed that
assumption as gc-app now adds that annotation to every service, causing apps
that don't use the vault: prefix (currently everything) to crash loop.

with this change in our fork of envconsul, we no longer have to worry about
envconsul hanging when no secrets are provided.

cmd/theatre-envconsul/main.go

@@ -140,10 +140,6 @@ func mainError(ctx context.Context, command string) (err error) {
 			}
 		}
 
-		if len(secretEnv) == 0 {
-			return errors.New("no 'vault:' prefix found in config or environment")
-		}
-
 		envconsulConfig := execVaultOptions.EnvconsulConfig(secretEnv, vaultToken, *execTheatreEnvconsulBinary, *execCommand)
 		configJSONContents, err := json.Marshal(envconsulConfig)
 		if err != nil {