Add endpoint for getting addresses

[PhantomWatson]

Add a public endpoint such as GET /address that takes a locationName input and outputs the most recent address associated with that location. In the future, this could be upgraded to use the Google Maps API to determine the canonical address for a location.

// Controller code
    /**
     * Returns the address most recently associated with the provided location name
     *
     * @return void
     */
    public function getAddress()
    {
        $location = (string)$this->request->getData('location');
        $address = $location ? $this->Events->getAddress($location) : false;
        $this->viewBuilder()->setClassName('Json');
        $this->set([
            'address' => $address,
            '_serialize' => ['address']
        ]);
    }

// Table code
    /**
     * Returns the most recently published address for the provided location name or FALSE if none is found
     *
     * @param string|null $location Location name
     * @return string|boolean
     */
    public function getAddress($location)
    {
        if (!$location) {
            return false;
        }

        /** @var Event|null $result */
        $result = $this->find()
            ->select(['Events.address'])
            ->where([
                'Events.published' => true,
                'Events.location' => $location,
                'Events.address NOT' => ''
            ])
            ->orderDesc('Events.created')
            ->first();

        return $result ? $result->address : false;
    }