Text normalization
This pull request **introduces 9 alerts** when merging 1f4320a27481466e8223cf8c37375a6f529d7221 into 08d1ccc503e35796e2874b24eca677e9eebad71c - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-95caec7dea0dda6c9d810101bc940f1b7fcbe7f0)

**new alerts:**

* 3 for Except block handles &#39;BaseException&#39;
* 3 for Unused import
* 2 for Unused local variable
* 1 for Comparison of constants This pull request **introduces 4 alerts** when merging 8fcb060ad660afba3c0c18f66fadf19b6a591f33 into 08d1ccc503e35796e2874b24eca677e9eebad71c - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-1caf3d54580f674d744a5163396a7f3dace0978b)

**new alerts:**

* 3 for Except block handles &#39;BaseException&#39;
* 1 for Comparison of constants This pull request **introduces 4 alerts** when merging a5ac274b377cc86064482e431dd69ee9cb5c4c68 into 08d1ccc503e35796e2874b24eca677e9eebad71c - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-e358af38a187868e9fee123f45c1a075333c6e29)

**new alerts:**

* 3 for Except block handles &#39;BaseException&#39;
* 1 for Comparison of constants This pull request **introduces 4 alerts** when merging ba2af6f3b9111367b2513d5e2a84b02eb1db6dd5 into 08d1ccc503e35796e2874b24eca677e9eebad71c - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-bf9d19eb66ac9a1ea3a08bd19df118bef5be049c)

**new alerts:**

* 3 for Except block handles &#39;BaseException&#39;
* 1 for Comparison of constants This pull request **introduces 4 alerts** when merging ad0e8cdf9bea1c2db50eb33b1c61bb83a76a36e9 into 9da1d27ddd7f1d5d9b6cd75f7308787976680dd8 - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-0c0639bdacc1eba624c84b35486129114651b4b3)

**new alerts:**

* 3 for Except block handles &#39;BaseException&#39;
* 1 for Comparison of constants This pull request **introduces 4 alerts** when merging be92477cd301a13ae6d223a09b490cf2a81508dd into 9aa4ada92b2e6ddd418704dc392e8576d44e5f41 - [view on LGTM.com](https://lgtm.com/projects/g/NVIDIA/NeMo/rev/pr-c6a60db3032019e55dea98b121d785892bd73fb5)

**new alerts:**

* 3 for Except block handles &#39;BaseException&#39;
* 1 for Comparison of constants
* Added rule-based text normalization for TTS
* added pytests
* added tutorial 