Add graphql server (#27)

* Add graphql server

* Update Makefile

* Update log_filters constraint

* Add GetLogFilter to repo

* Update travis (use Makefile, go fmt, go vet)

* Add logFilter schema and resolvers

* Add GetWatchedEvent to watched_events_repo

* Add watchedEventLog schema and resolvers

db/migrations/1517854395_update_log_filters_to_block_constraint.down.sql

@@ -0,0 +1,7 @@
+BEGIN;
+ALTER TABLE log_filters
+  DROP CONSTRAINT log_filters_to_block_check;
+
+ALTER TABLE log_filters
+  ADD CONSTRAINT log_filters_from_block_check1 CHECK (to_block >= 0);
+COMMIT;

db/migrations/1517854395_update_log_filters_to_block_constraint.up.sql

@@ -0,0 +1,7 @@
+BEGIN;
+ALTER TABLE log_filters
+  DROP CONSTRAINT log_filters_from_block_check1;
+
+ALTER TABLE log_filters
+  ADD CONSTRAINT log_filters_to_block_check CHECK (to_block >= 0);
+COMMIT;