[Enhancement] Optionally use the YouTube API for improved fast indexing (#282)

* Started adding youtube API for fast indexing

* Hooked youtube API into fast indexing

* Added youtube_api_key to settings

* Added youtube api key to settings UI

* Added tests

* Refactored the youtube api module

* More refactor

* Changed editing mode name from basic to standard

* [WIP] started on copy changes

* Updated copy

lib/pinchflat/sources/source.ex

@@ -129,7 +129,7 @@ defmodule Pinchflat.Sources.Source do
   @doc false
   def fast_index_frequency do
     # minutes
-    15
+    10
   end
 
   @doc false