Boto dynamodb module should be using layer 2 abstractions

[l2ol33rt]

The boto_dynamodb module was using the layer1 abstractions after the refactor to utils.boto. It originally was using the layer2 abstractions: 5f7bd48

Noticed this after trying to run:

salt 'salt-master' boto_dynamodb.exists salt-master-store

This returned:

salt-master:
    Passed invalid arguments to boto_dynamodb.exists: list indices must be integers, not str

        Check to see if a table exists.

        CLI Example:

        .. code-block:: bash

            salt myminion boto_dynamodb.exists table_name region=us-east-1

This was due to the layer1 abstractions that return a list of tables instead of a dictionary (which the salt module was expecting). With the layer2 abstraction change was tested successfully against create_table, exist and delete in the boto_dynamodb module:

~# salt salt-master boto_dynamodb.create_table salt-master-store1 hash_key=id hash_key_data_type=N range_key=created_at range_key_data_type=N read_capacity_units=1 write_capacity_units=1
salt-master:
    True

~# salt salt-master boto_dynamodb.exists salt-master-store1
salt-master:
    True

~# salt salt-master boto_dynamodb.delete salt-master-store1                                                                                                                                     
salt-master:
    True

Salt versions:

Salt Version:
           Salt: 2015.8.0rc3-174-g35a5fad

Dependency Versions:
         Jinja2: 2.7.2
       M2Crypto: 0.21.1
           Mako: Not Installed
         PyYAML: 3.10
          PyZMQ: 14.0.1
         Python: 2.7.6 (default, Jun 22 2015, 17:58:13)
           RAET: Not Installed
        Tornado: 4.2.1
            ZMQ: 4.0.4
           cffi: Not Installed
       cherrypy: Not Installed
       dateutil: Not Installed
          gitdb: Not Installed
      gitpython: Not Installed
          ioflo: Not Installed
        libnacl: Not Installed
   msgpack-pure: Not Installed
 msgpack-python: 0.3.0
   mysql-python: Not Installed
      pycparser: Not Installed
       pycrypto: 2.6.1
         pygit2: Not Installed
   python-gnupg: Not Installed
          smmap: Not Installed
        timelib: Not Installed

System Versions:
           dist: Ubuntu 14.04 trusty
        machine: x86_64
        release: 3.13.0-52-generic
         system: Ubuntu 14.04 trusty