Added HTTP_Negotiate scheme and helper to support Negotiate Authorization. The fall back case handled to submit a form in case authorization is not perfomed through SPNEGO
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Updated method comments
Merge remote-tracking branch 'upstream/2.1' into 2.1
Merge pull request #18 from onkar-dhuri/2.1

Added HTTP_Negotiate scheme and helper to support Negotiate Authorization. The fall back case handled to submit a form in case authorization is not perfomed through SPNEGO