Table definitions in attributes

This commit adds flexibility to table definitions by:
 - allows table definitions to be defined entirely in attributes using a hash in the node['dynamic-dynamodb']['config']['tables'] attribute.
- allows filtering the defined tables from the data bag using an array of table names in the node['dynamic-dynamodb']['config']['tables'] attribute.
- allows specifying the data_bag and data_bag_item names for both table definitions and aws credentials

The default behavior should not be changed as the attribute defaults are set to the same values as before.