Remove invalid releases automatically (#466)

Automatically remove empty releases or releases which are released in the future, regardless of the product.

Also refactored a bit releasedata.py to use better names and clarify types.

releases/ansible.json

@@ -1,39 +1,5 @@
 {
-  "releases": {
-    "9": {
-      "name": "9"
-    },
-    "8": {
-      "name": "8"
-    },
-    "7": {
-      "name": "7"
-    },
-    "6": {
-      "name": "6"
-    },
-    "5": {
-      "name": "5"
-    },
-    "4": {
-      "name": "4"
-    },
-    "3": {
-      "name": "3"
-    },
-    "2.9": {
-      "name": "2.9"
-    },
-    "2.10": {
-      "name": "2.10"
-    },
-    "11": {
-      "name": "11"
-    },
-    "10": {
-      "name": "10"
-    }
-  },
+  "releases": {},
   "versions": {
     "11.7.0": {
       "name": "11.7.0",