mbed device-management init does not seem to work

I get this error:
```
C:\se\mbed-cloud-client-example-internal>mbed device-management init -d arm.com --model-name k64f

[mbed] Working path "C:\se\mbed-cloud-client-example-internal" (program)
Traceback (most recent call last):

File "C:\se\mbed-cloud-client-example-internal\mbed-os\tools\device_management.py", line 192, in
main()

File "C:\se\mbed-cloud-client-example-internal\mbed-os\tools\device_management.py", line 187, in main
}[options.action](options) or 0

File "C:\se\mbed-cloud-client-example-internal\mbed-os\tools\device_management.py", line 120, in inner
"key": api_key_value

File "c:\python27\lib\site-packages\mbed_cloud\pagination.py", line 150, in next
return self.__next__()

File "c:\python27\lib\site-packages\mbed_cloud\pagination.py", line 159, in __next__
raise StopIteration()
StopIteration

[mbed] ERROR: "c:\python27\python.exe" returned error.

Code: 1

Path: "C:\se\mbed-cloud-client-example-internal"

Command: "c:\python27\python.exe -u C:\se\mbed-cloud-client-example-internal\mbed-os\tools\device_management.py init -d arm.com --model-name k64f"

Tip: You could retry the last command with "-v" flag for verbose output
```