finishing porting omni watcher to work with light sync; split into full, light,

and shared directories and refactor as much into shared; finish
lightSync omni watcher tests

db/migrations/1532468317_create_checked_headers_table.up.sql

@@ -1,5 +1,4 @@
 CREATE TABLE public.checked_headers (
   id                  SERIAL PRIMARY KEY,
-  header_id           INTEGER UNIQUE NOT NULL REFERENCES headers (id) ON DELETE CASCADE,
-  price_feeds_checked BOOLEAN NOT NULL DEFAULT FALSE
+  header_id           INTEGER UNIQUE NOT NULL REFERENCES headers (id) ON DELETE CASCADE
 );