Authentication fails with "TypeError: Incorrect padding"

*I'm submitting a ...*
- [x] bug report
- [ ] feature request
- [ ] support request

## General information

Updated my RaspberryPi3 running latest stable LibreElec to the latest Leia build (build no. 125), installed widevine using the standard script, installed Netflix plugin by downloading the latest master from this git repo as a ZIP.

### Prerequisites

* [x] Are you running the latest version?

### Description

Plugin installs, on first run, it asks for credentials. When these are provided, the entry in the folder listing shows the user, selecting the user results in the message that the Netflix addon encountered an error.

When Kodi now starts, Netflix already throws an error.

### Steps to Reproduce

1. Boot LibreElec
2. Done

**Expected behavior:** No errors, Netflix at least browsable.

**Actual behavior:** Error when Kodi is started, Netflix not browsable (or playable)

## Context (Environment)

### Installation

Tried both:

* [x] I installed the plugin via zip from the Releases page - 0.12.7
* [ ] I´m using the Netflix Repo
* [x] I´m using a different source (Please tell which) - current master as of 26.01.2018

### Operating System

* [ ] Linux (x86/x64)
* [ ] OSX (x86/x64)
* [ ] Windows (x86/x64)
* [x] Linux (ARM) - RPI3
* [ ] Android

## Debug log

[https://pastebin.com/VvcgQe8E](https://pastebin.com/VvcgQe8E)

## Other information

It looks like this is the issue:
```
17:18:34.354 T:1631515536 ERROR: EXCEPTION Thrown (PythonToCppException) : -->Python callback/script returned the following error<--
- NOTE: IGNORING THIS CAN LEAD TO MEMORY LEAKS!
Error Type:
Error Contents: Incorrect padding
Traceback (most recent call last):
File "/storage/.kodi/addons/plugin.video.netflix/service.py", line 16, in
from resources.lib.NetflixHttpRequestHandler import NetflixHttpRequestHandler
File "/storage/.kodi/addons/plugin.video.netflix/resources/lib/NetflixHttpRequestHandler.py", line 30, in
netflix_session=NETFLIX_SESSION)
File "/storage/.kodi/addons/plugin.video.netflix/resources/lib/NetflixHttpSubRessourceHandler.py", line 28, in __init__
self.credentials = self.kodi_helper.get_credentials()
File "/storage/.kodi/addons/plugin.video.netflix/resources/lib/KodiHelper.py", line 173, in get_credentials
'password': self.decode(enc=password)
File "/storage/.kodi/addons/plugin.video.netflix/resources/lib/KodiHelper.py", line 203, in decode
enc = base64.b64decode(enc)
File "/usr/lib/python2.7/base64.py", line 78, in b64decode
TypeError: Incorrect padding
-->End of Python script error report<--
```