Change icon helper input params

[jokklan]

I often want to add html options like a class to my icons, but it's not very often i want to have text. That means that i end up writing nil all the time (fx. <%= icon :user, nil, class: "color-blue" %>).

This pull request should fix that problem, and still be backwards compatible :)

Before:

<%= icon :spinner, nil, class: "fa-spin" %>
#=> <i class="fa fa-spinner fa-spin"></i>

<%= icon :spinner, class: "fa-spin" %>
#=> <i class="fa fa-spinner">{ class: "fa-spin"}</i>

<%= icon :spinner, "Loading", class: "fa-spin" %>
#=> <i class="fa fa-spinner fa-spin">Loading</i>

After

<%= icon :spinner, nil, class: "fa-spin" %>
#=> <i class="fa fa-spinner fa-spin"></i>

<%= icon :spinner, class: "fa-spin" %>
#=> <i class="fa fa-spinner fa-spin"></i>

<%= icon :spinner, "Loading", class: "fa-spin" %>
#=> <i class="fa fa-spinner fa-spin">Loading</i>

[jokklan]

no :D?

[prdolmos]

I agree with this; it makes it much more readable, and I see no downside given the backwards compatibility.

[prdolmos]

I just noticed this is similar to #33

[raldred]

+1 for consolidating these arguments. It should behave like content_tag.
I don't think there's a single instance where I use anything other than an empty string.

@supercodepoet can we get this merged please.

[jokklan]

Sorry you are right @trinibago, fixed here: #89, or you can revert and merge #33 which is basically the same.