Correcting couple of bugs in example an tutorial
This pull request **introduces 1 alert** when merging 260e2af8a0d4ea45c2f7ce8cfec9f17fc52a3912 into d01b7bbc3fdb1bbf14789f71b8f368cf0aa8f86b - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-838abc09fd547a8fab60739d22febc15820ebfe7)

**new alerts:**

* 1 for Unused import @vladgets  can you please fix CI on this PR?
 Correcting it. The problem was in the previous commits exp_manager was removed from testing my model in Jenkins file. And my code was relying for it to save the model.