Add missing constant to Elastica\Filter\GeoDistance
Add missing constant to Elastica\Filter\GeoDistance

From http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/query-dsl-geo-distance-filter.html#_options_4

stof/Elastica,ARAMISAUTO/Elastica,kartikm/Elastica,JustinHook/Elastica,im-denisenko/Elastica,jeancsil/Elastica,vlajos/Elastica,Jmoati/Elastica,pborreli/Elastica,piotrantosik/Elastica,webdevsHub/Elastica,pborreli/Elastica,0x46616c6b/Elastica,fubuki/Elastica,miniplay/Elastica,im-denisenko/Elastica,Southparkfan/Elastica,splitice/Elastica,giorrrgio/Elastica,Gasol/Elastica,miniplay/Elastica,Mosoc/Elastica,JustinHook/Elastica,falconavs/Elastica,0x46616c6b/Elastica,Mosoc/Elastica,ebernhardson/Elastica,sugarcrm/Elastica,piotrantosik/Elastica,giovannialbero1992/Elastica,revinate/Elastica,p365labs/Elastica,vlajos/Elastica,Gasol/Elastica,jeancsil/Elastica,ebernhardson/Elastica,ruflin/Elastica,eilgin/Elastica,revinate/Elastica,p365labs/Elastica,stof/Elastica,kartikm/Elastica,fubuki/Elastica,ARAMISAUTO/Elastica,tmatei/Elastica,Southparkfan/Elastica,webdevsHub/Elastica,Jmoati/Elastica,giorrrgio/Elastica,giovannialbero1992/Elastica,eilgin/Elastica,tmatei/Elastica,ewgRa/Elastica,ewgRa/Elastica,markeilander/Elastica,markeilander/Elastica,falconavs/Elastica,sugarcrm/Elastica