add registry item for Harmonizome

[andrewsu]

Harmonizome has precomputed 139800 gene-disease perturbation associations based on GEO. Would be very useful to add these to the Translator API network.

Example API call to query by gene symbol (retrieving data sets in which it is differentially expressed): http://amp.pharm.mssm.edu/Harmonizome/api/1.0/gene/nanog?showAssociations=true

Example API call to query by data set (retrieving all genes that are differentially expressed): http://amp.pharm.mssm.edu/Harmonizome/api/1.0/gene_set/V/Allen+Brain+Atlas+Adult+Human+Brain+Tissue+Gene+Expression+Profiles