replaced map of singletons in backend with single singleton

service/mget.js

@@ -23,7 +23,7 @@ function service( backend, query, cb ){
   };
 
   // query new backend
-  backend().client.mget( cmd, function( err, data ){
+  backend.client.mget( cmd, function( err, data ){
 
     // log total ms elasticsearch reported the query took to execute
     if( data && data.took ){

service/search.js

@@ -10,7 +10,7 @@ var logger = require( 'pelias-logger' ).get( 'api' );
 function service( backend, cmd, cb ){
 
   // query new backend
-  backend().client.search( cmd, function( err, data ){
+  backend.client.search( cmd, function( err, data ){
 
     // log total ms elasticsearch reported the query took to execute
     if( data && data.took ){

src/backend.js

@@ -1,14 +1,5 @@
-var config = require( 'pelias-config' ).generate().esclient;
+const config = require( 'pelias-config' ).generate().esclient;
-var Backend = require('geopipes-elasticsearch-backend'),
+const Backend = require('geopipes-elasticsearch-backend');
-    client = require('elasticsearch').Client(config),
+const client = require('elasticsearch').Client(config);
-    backends = {};
 
-function getBackend( index, type ){
+module.exports = new Backend(client);
-  var key = ( index + ':' + type );
-  if( !backends[key] ){
-    backends[key] = new Backend( client, index, type );
-  }
-  return backends[key];
-}
-
-module.exports = getBackend;

test/unit/mock/backend.js

@@ -89,7 +89,7 @@ function setup( key, cmdCb ){
       }
     };
   }
-  return backend;
+  return backend();
 }
 
 function mgetEnvelope( options ){