JSONLoader: Code clean up.

src/loaders/JSONLoader.js

@@ -54,7 +54,7 @@ THREE.JSONLoader.prototype.loadAjaxJSON = function ( context, url, callback, tex
 
 				} else {
 
-					console.warn( "THREE.JSONLoader: [" + url + "] seems to be unreachable or file there is empty" );
+					console.error( 'THREE.JSONLoader: "' + url + '" seems to be unreachable or the file is empty.' );
 
 				}
 
@@ -66,7 +66,7 @@ THREE.JSONLoader.prototype.loadAjaxJSON = function ( context, url, callback, tex
 
 			} else {
 
-				console.error( "THREE.JSONLoader: Couldn't load [" + url + "] [" + xhr.status + "]" );
+				console.error( 'THREE.JSONLoader: Couldn\'t load "' + url + '" (' + xhr.status + ')' );
 
 			}
 
@@ -76,7 +76,7 @@ THREE.JSONLoader.prototype.loadAjaxJSON = function ( context, url, callback, tex
 
 				if ( length === 0 ) {
 
-					length = xhr.getResponseHeader( "Content-Length" );
+					length = xhr.getResponseHeader( 'Content-Length' );
 
 				}