added support to define classNames in allowIn

[djusv]

I needed this for a particular case and I thought I would share my code.

[chieffancypants]

What is the particular case?

[djusv]

I had 2 input element visible on 1 page = 1-search-input, 2-textbox-message-input.

I didn't want the hotkey-action to be called when the user was typing in input#1 but the hotkey-action should be triggered when the user had focus on input#2 triggered the combo.