TLT integration
This pull request **introduces 3 alerts** when merging f88d17c8c9e18e5ab54c92daa1ad4507bc2b9db6 into cd55594e0f60a4bcbaf6d0e4196c1404591e0076 - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-cd7113f9f6c4a6d00463f645cd84fd574adb297f)

**new alerts:**

* 2 for Unused import
* 1 for Unused local variable This pull request **introduces 3 alerts** when merging 82039f3fb78ac30be9199056082e0c7bfe5d5704 into 16a94758d2dafe7af8aa5bef504cf0584ed7d905 - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-78e1e8cd47bfa077824ae972cd863a6354f37cb1)

**new alerts:**

* 2 for Unused import
* 1 for Unused local variable This pull request **introduces 3 alerts** when merging 0d97efdfe7acdf66b07b22b9ef6998ccb8288d33 into 89579d87649c894fd5c74892308d4ac0b07dec4d - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-38f6f286471ed1a78730362ef5ae968f61fbe124)

**new alerts:**

* 2 for Unused import
* 1 for Unused local variable This pull request **introduces 3 alerts** when merging 00e01e7951e3a7079a88f4df6c5917834cecc4b5 into 2da227a757857fcbd578bad3ba6292de2230ea3d - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-b560759e6b5db0a69d3f9c2b307b7333e9877468)

**new alerts:**

* 2 for Unused import
* 1 for Unused local variable This pull request **introduces 3 alerts** when merging 762b26a9f5ff4012229c0aee7cb4a22dc857d1c8 into b2916578ff7616dcf7d99e3ec5ce98294fa45e91 - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-1b08fca26be2960f5071a99e6644c983e65a1442)

**new alerts:**

* 2 for Unused import
* 1 for Unused local variable
The branch contains up to date changes required for models ported to TLT to work.

- changes to Token Classification Model (NLP)
- changes related to Question Answering (NLP)
- changes related to Punctuation Model (NLP)