convert all keys to strings on write

index.js

@@ -556,6 +556,7 @@ Dat.prototype._commit = function (links, type, operations, message, cb) {

    for (var i = 0; i < operations.length; i++) {
      var op = operations[i]
      op.key = op.key.toString()
      var val = messages.Operation.encode(op)

      if (op.content === FILE) files++