Make arrows + close customizable

[webgefrickel]

Just as a small idea: would it be possible to make the markup for the arrows and the close-function customizable? So basically just move those three vars into the options-object? This way I could more easily modify the look and feel of baguetteBox.

I am happy to create a pull request if you think this is a good idea.

[feimosi]

Hi, sure, make a PR. I can then take a look and assess whether it fits well.

[xavierve]

yes, having control over action buttons will be great. Thanks for great code!

[jackbarham]

This would be awesome. SlickSlider has an option, such as:

rightArrow: '<i class="fa fa-arrow-right"></i>'

Which is really useful :)

[Olli]

I also need this function - #204