add data-trunk8-* support

add attribute  data-trunk8-* to each element for special settings
@rviscomi sorry for my english,i am uncertain if i understand your words
<pre>It should not take precedence over the options object in init.</pre>
the order of the config is :
trunk8.defaults -- trunk8 config -- element attribute
 and the next will override the last
Space after "if".

Save "data-trunk8-" to a variable, "trunk8DataAttributeName".