init rust db backend

lootalot_db/migrations/2019-06-10-123940_create_players/down.sql

@@ -0,0 +1 @@
+DROP TABLE players;

lootalot_db/migrations/2019-06-10-123940_create_players/up.sql

@@ -0,0 +1,9 @@
+CREATE TABLE players (
+  id INTEGER PRIMARY KEY,
+  name VARCHAR NOT NULL,
+  debt INTEGER DEFAULT 0, -- debt to the group in copper pieces
+  cp INTEGER DEFAULT 0,
+  sp INTEGER DEFAULT 0,
+  gp INTEGER DEFAULT 0,
+  pp INTEGER DEFAULT 0
+);