Added an ability to search using geo-spatial queries and filter documents by expression

[gkozlenko]

I've added two methods to Query module for geo-spatial search:

• spatial
• expressionFilter

Basic usage:

var solr = require('./../lib/solr');
var client = solr.createClient();
var query = client.createQuery()
    .spatial({
        pt: '37.7749295,-122.4194155',
        sfield: 'location_srpt',
        d: 10
    }).expressionFilter('{!geofilt}');

It will find all documents which are located in 10 km radius of the chosen point.

[ColadaFF]

Hi there,

Can you add the tests for this feature? Then I can merge the pull request.

[lstone]

Would love to see this merged once tests are written.