InternetHelper incorrectly sets both "Transfer-Encoding: chunked" & "Content-Length" headers

[martyngigg]

A HTTP message using any Transfer-Encoding other than identity should not set the Content-Length header - see HTTP protocol. This is currently done in InternetHelper::createRequest.

Servers are supposed to ignore the Content-Length if Transfer-Encoding is specified but at the time this issue was created there was an problem with the proxy servers at RAL mangling the data if both of these header fields were present. This manifests itself by not allowing:

• uploads to the script repository
• posting of usage data
  if you are on the RAL network.

To reproduce the problem (only currently reproducible at ISIS):

• Open your Mantid.user.properties and add

UploaderWebServer=http://upload.mantidproject.org/scriptrepository?debug=1
# Base Url for the remote script repository. Not necessarily accessible, it is used to construct longer URLs
ScriptRepository=http://download.mantidproject.org/dev-scriptrepository/

• Open MantidPlot, select File->Script Repository and choose an install location
• Make some change to one of the files (this is a debug repository so no need to worry about user data)
• Click Reload and then click the Upload button that appears next to the changed file
• After filling in the required information, click OK and the upload will fail.