Configurable parameter insertAfter and insertBefore overriden by default

[pp-surbhigupta]

When integrating the Plugin, I faced an issue that my content was not getting replaced at the position mentioned in the configuration

$('#scrollableList').endlessScroll({
fireOnce: false,
inflowPixels: 1,
insertAfter: '#scrollableList div:last',
insertBefore: '#scrollableList div:last',
loader: ''
});

insertAfter and insertBefore were overriden in the function EndlessScroll.prototype.setInsertPositionsWhenNecessary since we are using default to check if insertAfter and insertBefore are provided. We should be checking for options.insertAfter and options.insertBefor