Allow for listing roles for users. Specify security setting match address

[guidograzioli]

Fix #12
Fix #16

While this changeset originates from a bug report, the solution involves refactoring the key in the activemq_users dictionary from role: str to roles: list(str), thus it is marked as major_change

Example configuration:

    activemq_users:
      - user: amq
        password: amqbrokerpass
        roles: [ admin ]
      - user: other
        password: amqotherpass
        roles: [ consumer, producer ]
    activemq_roles:
      - name: admin
        permissions: [ createNonDurableQueue, deleteNonDurableQueue, createDurableQueue, deleteDurableQueue, createAddress, deleteAddress, consume, browse, send, manage ]
      - name: consumer
        match: topics.#
        permissions: [ consume, browse ]
      - name: producer
        match: topics.#
        permissions: [ send, browse ]