Fix small bug on ReadMinds for add_column down

Hi Rob,

  Not totally sure it's the right way to do this or if you accept any pull request, still here is a small contribution:

1) On The Migrator.ReadMinds method, on the add_column there were no .table to get the table name from the migration object. That caused an exception when there were no "down" element in the js file.

2) I've also changed the Program.GetNameStub method to return a pad identifier with a 5 '0' instead of the if/else if/else that was present.

3) Added a .gitignore file.