ContentType is missing in creation of signature

Hi,

first very good module I learned a lot :)
Sadly during the creation of the singnature when using "Get-AzureBlobContainerBlobs" I found that the ContentType (application/octet-stream) was missing but send as header therefor the signatures differ. Because application/octet-stream is the default I created a workaround inside GetTokenStringToSign:

(...)
        if($RangeEnd -gt 0)
        {
            $Range="bytes=$($RangeStart)-$($RangeEnd-1)"
        }
+        if ($ContentType -eq "") {
+            $ContentType = "application/octet-stream"
+        }
        $SigningPieces=@(
            $Verb,$ContentEncoding,
            $ContentLanguage,$LengthString,
            $ContentMD5,$ContentType,$Date,$IfModifiedSince,$IfMatch,$IfNoneMatch,$IfUnmodifiedSince,$Range
        )
(...)

But maybe it is better to change $TokenParams and $RequestParams inside Get-AzureBlobContainerBlobs (and all the other where it is missing)

Kind regards,
Ralf