Add filter for post meta / custom fields for the JSON output

[michaeltorbert]

We should add a custom field for the output at url.com/?sm-xml-search=1....... which is what our JavaScript (or someone else's JS or PHP potentially) can use to see the location data.

[michaeltorbert]

sm_location_fields is the name of the filter hook
The code looks like this:

$location_fields = array(
'location_address' => 'address',
'location_address2' => 'address2',
'location_city' => 'city',
'location_state' => 'state',
'location_zip' => 'zip',
'location_country' => 'country',
'location_phone' => 'phone',
'location_fax' => 'fax',
'location_email' => 'email',
'location_url' => 'url',
'location_special' => 'special',
);

$location_field_map = apply_filters( 'sm_location_fields', $location_fields );