Add onclick to button field

[kastoras]

Adds onclick functionality to Button Field:

When used on delete button, it add the code provided at onclick method, if not it add the code for form submission ('$("#form${id}").submit();')

Example to use this:
Button::make('id')->class(...)->route(...)->onclick('Add this to Buttons onclick tag') result: <button title="" data-toggle="" onclick="Add this to Buttons onclick tag" type="button" data-route="..." id="..." class="...">

[wimurk]

#12 refer to issue