Support custom configs

[Aergonus]

Sample command: ./kafka-topics.sh --create --topic test_create_topic --zookeeper localhost:2181 --partitions 10 --replication-factor 3 --config "compression.type=producer" --config "retention.ms=604800000"

This lets someone create a topic using the format

            {
              "topic": "test_create_topic",
              "partitions": 10,
              "replication_factor": 3,
              "configs": [
                "retention.ms=604800000",
                "compression.type=producer"
              ]
            },

Doing a delete with configs will cause failures, but alterations are allowed