Consul SDB treats all values as binary in Python 3

Description of Issue

When using the Consul SDB module, all values retrieved from the KV store are rendered as binary strings, rather than unicode when using Python 3. They should be decoded to unicode, or use the appropriate function from six to allow for appropriate behavior between 2 and 3.

Setup

In the master configuration:

    sdb:
      consul:
        driver: consul
        host: consul.service.consul

Steps to Reproduce Issue

Set a value in the Consul SDB and then render it out into a salt template using Jinja to load the SDB value. e.g. foo: {{ salt.sdb.get('sdb://consul/foo') }}

Versions Report

Salt Version:
           Salt: 2019.2.2
 
Dependency Versions:
           cffi: 1.13.2
       cherrypy: Not Installed
       dateutil: 2.5.3
      docker-py: Not Installed
          gitdb: 2.0.0
      gitpython: 2.1.1
          ioflo: Not Installed
         Jinja2: 2.8
        libgit2: 0.28.2
        libnacl: Not Installed
       M2Crypto: Not Installed
           Mako: Not Installed
   msgpack-pure: Not Installed
 msgpack-python: 0.4.8
   mysql-python: Not Installed
      pycparser: 2.19
       pycrypto: 2.6.1
   pycryptodome: Not Installed
         pygit2: 0.28.2
         Python: 3.5.3 (default, Sep 27 2018, 17:25:39)
   python-gnupg: Not Installed
         PyYAML: 3.12
          PyZMQ: 16.0.2
           RAET: Not Installed
          smmap: 2.0.1
        timelib: Not Installed
        Tornado: 4.4.3
            ZMQ: 4.2.1
 
System Versions:
           dist: debian 9.11 
         locale: UTF-8
        machine: x86_64
        release: 4.9.0-9-amd64
         system: Linux
        version: debian 9.11

Start at the Consul SDB implementation and trace the sdb.get('sdb://consul/foo') entry point on Python 3. Reproduce the value through a Salt Jinja template, then verify that retrieved KV values are Unicode while behavior remains compatible with Python 2. Done means the rendered value is no longer a binary string.