Added a @file section
get and set methods should now work correctly and return cached data. We have to massage a few things when passing data to DynamoDB (to ensure item limits are adhered to) as well as when data is returned (to ensure data is correctly decoded and passed back in the format Drupal Core/Contrib expects).

Comments have also been added to clarify these facts.
Added a README and allowed for the variable placement of the sdk.
Removed a line because neat.