Added protocol to Via Header

[JoaoSandrini]

Proposed changes

Changed the way the via header is constructed in order to enable compatibility with other NGSI-LD Context Brokers such as Scorpio Broker

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

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• I have added tests that prove my fix is effective or that my feature works
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Further comments

Added the protocol to the via header, in order to enable compatibility with other NGSI-LD Context Brokers such as Scorpio Broker. Now its constructed like / <current_domain> (Wirecloud-python-Proxy/1.1). Tested it in a local environment and works, not sure how to implement the tests to comprove but i'm up to learn how to or help with it if needed.

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[JoaoSandrini]

I have read the CLA Document and I hereby sign the CLA