Add support for schema dumps to allow db:setup and db:reset

[RichardBradley]

The rails migration system keeps the latest version of the schema in a schema.rb file (see http://guides.rubyonrails.org/migrations.html#schema-dumping-and-you )

This allows:

• An up to date schema reference to be kept in source control
• The rake task "db:setup" which allows installing a new instance without running all the migrations in turn
• The rake task "db:reset" for integration testing

[piotrooo]

I think it will be better when the db:reset will clear the entire database structure.