make lib compatible with log4js 3.x

[menshov-d]

function insert(loggingEvent) {
var options = getOptions();
var category;
if (loggingEvent.hasOwnProperty('logger.category')) {
category = loggingEvent.logger.category;
} else {
category = loggingEvent.categoryName;
}
if (collection) {
if (options.w === 0) {
// fast write
collection.insert({
timestamp: loggingEvent.startTime,
data: loggingEvent.data,
level: loggingEvent.level,
category: category
},options);
} else {
// save write
collection.insert({
timestamp: loggingEvent.startTime,
data: loggingEvent.data,
level: loggingEvent.level,
category: category
},options,function(error) {
if (error) {
console.error('log: Error writing data to log!');
console.error(error);
console.log('log: Connection: %s, collection: %, data: %j',config.connectionString,collectionName,loggingEvent);
}
});
}
} else {
cache.push(loggingEvent);
}
}