Remove status tracking code from PhylorefWrapper

[gaurav]

PhylorefWrapper.getCurrentStatus(), PhylorefWrapper.getStatusChanges() and PhylorefWrapper.setStatus() methods were once used to document changes in status in a phyloreference. I think our current intention is to remove this from PhylorefWrapper and to instead use external systems to track phyloref statuses (e.g. GitHub), except for deprecation. This issue covers removing those methods and associated tests, and replacing them with a simple deprecation system that allows us to mark a phyloref as deprecated (as per phyloref/klados#81). Anything else can be included in the curator notes.