Added ext_coinc (External Coincidence) as blessed tag.

gracedb/fixtures/initial_tags.json

@@ -54,5 +54,12 @@
   	"eventlogs": [],
 	"displayName": "Data Quality",
 	"name": "data_quality"}
+ },
+ {"pk": 12,
+  "model": "gracedb.tag",
+  "fields": {
+  	"eventlogs": [],
+	"displayName": "External Coincidence",
+	"name": "ext_coinc"}
  }
 ]

settings/default.py

@@ -44,6 +44,7 @@ BLESSED_TAGS = [
                  'psd',
                  'data_quality',
                  'sky_loc',
+                 'ext_coinc',
                  'strain',
                  'tfplots',
                  'sig_info',