Added dependency fontawesome package

[raiyankamal]

When the login form is used without installing the fontawesome package, the social media icons (FB, twitter etc.) don't show up. I was able to resolve this in my environment by adding the fontawesome package. I believe this package should be included as one of the dependencies.

[splendido]

I'm aware there are some default values for the icons set to FontAwesome classes...
...and I admit this is not the best.

At the same time, I'm not sure everyone would be fine by getting FontAwesome added by default.
I guess many people might have no intention to use it.

Does this makes any sense?

[raiyankamal]

I understand that some people may not intend to use FA, I myself didn't. But I had to get it anyways to make the icons show up.
If FA is not included as a dependency by default, we should at least mention somewhere in the docs that the icons are borrowed from the FA package. So that users can either install FA on their own or roll their own styling.