AADLoginForLinux : sudo: PAM authentication error: Conversation error

## Issue
Getting the following error when trying to **sudo** with the AD account:
```
$ sudo -i
sudo: PAM authentication error: Conversation error
```
Tried this on Centos 7.3/Ubuntu 18.04

## Workaround
Changing the line in **/etc/sudoers.d/aad_admins** from:
```
%aad_admins ALL=(ALL) ALL
```
to
```
%aad_admins ALL=(ALL) NOPASSWD: ALL
```
fixed the issue.

## Request to developers

Correct extension package either by updating the **aad_admins** file as per the workaround or add appropriate PAM rules.

Reproduce the sudo -i failure with an AD account on CentOS 7.3 or Ubuntu 18.04. Inspect the generated /etc/sudoers.d/aad_admins entry alongside the applicable PAM rules, then verify that sudo authentication works without requiring the NOPASSWD workaround.

Written by the indexing model from the issue text.