First pass of LN payment callbacks

proxy_docker/app/data/sqlmigrate20190104_0.1-0.2.sql

@@ -0,0 +1,15 @@
+PRAGMA foreign_keys = ON;
+
+INSERT INTO cyphernode_props (property, value) VALUES ("pay_index", "0");
+
+CREATE TABLE ln_invoice (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  bolt11 TEXT UNIQUE,
+  status TEXT,
+  callback_url TEXT,
+  calledback INTEGER DEFAULT FALSE,
+  callback_failed INTEGER DEFAULT FALSE,
+  inserted_ts INTEGER DEFAULT CURRENT_TIMESTAMP
+);
+CREATE INDEX idx_lninvoice_bolt11 ON ln_invoice (bolt11);
+CREATE INDEX idx_lninvoice_status ON ln_invoice (status);