Title processing changes

Fixed two bugs which make the inheritance of titles much more natural
1. If the content did not have a "head" tag, the decorator title would not be processed leaving the title blank.
 - updated the code to properly process the decorator title when the content head is null
2. When either the decorator title or content title are empty, the title pattern is being processed which is resulting in unnatural titles such as "Decorator Title -" instead of "Decorator Title"
 - updated the code to only process the title pattern if both decorator title and content title are not empty

Thanks for the great plugin!

- Justin