Added Page load and Scroll end Events

[adearriba]

Sorry if this is not a great PR. It is the first I've done for public projects.

I added 2 events that extend the flexibility of the library:

• ajaxinate.page:load : This event fires when a new page is loaded.
• ajaxinate.scroll:end : This event fires when there is no more pages left to load.

I've had to add those in my code since the callback forces me to handle everything in 1 place instead of being able to handle different things in different places of the code.

Hope it helps the project.

Best,
@adearriba

[adearriba]

The way to use these new events would be:

document.addEventListener('ajaxinate.page:load', event => {
    //event.detail.content contains the HTML element being added
    console.log(event.detail.content);
});

document.addEventListener('ajaxinate.scroll:end', event => {
    console.log('No more pages left');
});