Stable release of browser and API

Stable release of Molecular Oncology Almanac browser and API endpoints. Rather than returning index values, sources and features now return content.

Sources are now displayed as,

{
  "citation": "Pfizer Inc. Bosulif (bosutinib) [package insert]. U.S. Food and Drug Administration website. https://www.accessdata.fda.gov/drugsatfda_docs/label/2020/203441s018lbl.pdf. Revised June 2020. Accessed November 12, 2020.", 
  "doi": null, 
  "nct": "None", 
  "pmid": "None", 
  "source_id": 1, 
  "source_type": "FDA", 
  "url": "https://www.accessdata.fda.gov/drugsatfda_docs/label/2020/203441s018lbl.pdf"
}

and molecular features as,

{
  "attributes": [
    {
      "feature_type": "rearrangement", 
      "gene1": "BCR", 
      "gene2": "ABL1", 
      "locus": null, 
      "rearrangement_type": "Fusion"
    }
  ], 
  "feature_type": "rearrangement"
}

Initial release

Cutting a release to begin this practice. This may be a publication pre-release.