sql: fixed typo on sql schema and added cashier_tree.sql

sql/cashier.sql

@@ -28,5 +28,5 @@ CREATE TABLE IF NOT EXISTS withdraw_keypairs(
 );
 
 CREATE TABLE IF NOT EXISTS tree(
-	tree BLOB NOT NULL,
+	tree BLOB NOT NULL
 );

sql/cashier_tree.sql

@@ -0,0 +1,4 @@
+CREATE TABLE IF NOT EXISTS tree(
+	tree BLOB NOT NULL
+);
+

sql/tree.sql

@@ -1,4 +1,4 @@
 CREATE TABLE IF NOT EXISTS tree(
-	tree BLOB NOT NULL,
+	tree BLOB NOT NULL
 );