BioSamples ISA JSON repository API needs to return a path like structure for its accessions

[bedroesb]

Currently the API return upon successful submission:

{
  "targetRepository" : "biosamples",
  "accessions" : [ {
    "id" : "SAMEA131351359"
  }, {
    "id" : "SAMEA131351360"
  } ]
}

But notice that normally the accession object contains the path of the ISA JSON, and not only the accession, see our repository api document.

Originally posted by @bedroesb in #44 (comment)