avoiding number_format expects double error

Under some circumstances `number_format` can return an error since it expects the var type to be `double`.

Now we're casting to make sure we get the proper type of var.
Merge pull request #2306 from curtismchale/patch-1

avoiding number_format expects double error
Should solve #2310
Add class name to "remove" button in cart template.

The remove button in the default cart template doesn't have a class name. This makes it awkward to add a css style to it while developing themes. I have added a class name of "edd-cart-remove-item-btn" so that styles may easily be applied.
Hyphens to Underscores on Class Name
Merge pull request #2321 from mintplugins/master

Add class name to "remove" button in cart template.
Merge branch 'master' into release/2.0