refactor(core): Allow tokenManager creation if IAM URL is not in VCAP_SERVICES

Author: lpatino10

core/src/main/java/com/ibm/watson/developer_cloud/service/WatsonService.java

@@ -103,7 +103,7 @@ public WatsonService(final String name) {
     this.name = name;
     String iamApiKey = CredentialUtils.getIAMKey(name);
     String iamUrl = CredentialUtils.getIAMUrl(name);
-    if (iamApiKey != null && iamUrl != null) {
+    if (iamApiKey != null) {
       IamOptions iamOptions = new IamOptions.Builder()
           .apiKey(iamApiKey)
           .url(iamUrl)