Fix invalid HTTP and a minor performance fix

Hi,

Please pull from my fixes branch.

$ git shortlog master..
Steven Post (2):
      Don't use chunking in the Base64 strings
      Make helper class static

That first commit is the most important one, without it, no valid request is ever done.
The library seems a but untested to me, since even the basic example doesn't work without this patch.
The core of the issue is the Base64 chunking, which adds whitespace (carriage return + line feed (\r\n)), this causes the backend server to fail over the invalid HTTP. Secondly, it causes an invalid signature, since the whitespace is also signed, but not included in the calculation on the server side.

Best regards,
Steven