Changed object properties to methods in order to get this to work with mocks. When running `sls invoke test` isOffline() will return false. Therefore, you must set IS_OFFFLINE=true as environment variable manually prior running test locally or you can add to your tests:

    before((done) => {
        process.env.IS_OFFLINE = true;
        ...
        done();
    });

and

    after((done) => {
        delete process.env.IS_OFFLINE;
        ...
        done();
    });

In the code use: `docClient = dynamodb.doc()` instead of `const docClient = dynamodb.doc`.
This will work with AWS, serverless offline and mocks.

Additionally, made ESLint changes.