fix unit tests
Initial implementation of ddb client. GetItem is the only implemented operation.
Provide dummy keys in unittest so tests will run if not set in environment
Merge branch 'unittest' into ddb
Unit tests for ddb
Fix dialyzer issues
DeleteItem implementation
put_item implementation
UpdateItem support
Merge pull request #30 from talko/unittest

unit tests
Add error handling
Fix get_item when the item isn't found or no attributes are returned
Query support
BatchGetItem implementation
BatchWriteItem implementation
More tests and bug fixes
CreateTable implementation
DeleteTable implementation
DescribeTable implementation
ListTables implementation
UpdateTable implementation