omia: add disease id mappings; omia-mp assoc; filter omim genes
omia: add disease id mappings; omia-mp assoc; filter omim genes

* create hardcoded map of grouping categories to disease ids.  #212
* add omia-to-mp associations; these are reportedly incomplete
* use OMIM source to filter out any omim genes from the omia-to-omim map
* add all omim diseases as being modeled by the various breeds (these were filtered out previously when >1 omim:omia).  still do not add these as anything other than xrefs to the omia disease id otherwise

monarch-initiative/dipper,TomConlin/dipper,monarch-initiative/dipper,TomConlin/dipper,monarch-initiative/dipper