FIX: errors running rake db:migrate while creating a table

For your reference the versions I have on my `Gemfile.lock`:

- activerecord (4.1.5)
- pg (0.17.1)
As an another problem, the table name such like "aaa'xxx" (including single quote) is not correctly handled.  Also it might cause SQL injection.

I think quote_table_name method should be rewritten for Redshift --- current (PostgreSQL) version of quote_table_name simply does not work.