fix error message on Import-SpoonImage

If we do not convert the message to a string, $stringdata is created as
a System.Object and throws Cannot convert System.Object[] to the type
'System.String' required by parameter 'Message' at Write-Verbose
$stringdata (test on a clean machine).
fix error on logout

Adding wildcards, otherwise an error is thrown because user and timedate
are unique.
fix for Convert-SpoonContainerToImage

- should specify ID otherwise the image will not be created
- convert $stringdata to string, so it can be printed by write-verbose
Merge pull request #1 from olegsomphane/master

Fixed a couple of error messages.