Function advertiseRefGenerator

this is the main method for generating the smart HTTP response for the reference discovery phase. The server advertises the available references

Servers MUST terminate the response with the magic 0000 end pkt-line marker.

The returned response is a pkt-line stream describing each ref and its known value. The stream SHOULD be sorted by name according to the C locale ordering. The stream SHOULD include the default ref named HEAD as the first ref. The stream MUST include capability declarations behind a NUL on the first ref.

Smart_reply     =  PKT-LINE("# service=$servicename" LF)
                   "0000"
                   *1("version 1")
                   ref_list
                   "0000"
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referenceList is called for generating the ref_list stage.