Add source and sequence fields to Gene model

Closes #96

This add the source and sequence fields to the Gene model.

It also makes sure that all genes are stated coming from IGC for those that currently exists in db. This might evolve in the future as a dedicated model in db to have more information about the source.

backend/metagenedb/apps/catalog/admin/gene.py

@@ -7,7 +7,8 @@ from metagenedb.apps.catalog.models import Gene
 class GeneAdmin(admin.ModelAdmin):
     exclude = ('functions', 'taxonomy')
 
-    list_display = ('gene_id', 'name', 'length', 'get_functions', 'get_taxonomy')
+    list_display = ('gene_id', 'source', 'name', 'length', 'get_functions', 'get_taxonomy')
+    list_filter = ('source',)
     search_fields = ('name',)
 
     def get_functions(self, obj):