Code review request: FLUID-852 patch

[Anastasia Cheetham]

If there's anyone out there who isn't on vacation, I'd appreciate a  
code review:

I've attached a patch file to FLUID-852:
http://issues.fluidproject.org/browse/FLUID-852

This patch implements a pluggable 'invitation text' to be used by the  
Inline Edit whenever the text is empty. This is the first step in  
responding to the recent discussions on how to deal with empty fields.

The patch doesn't style the invitation text yet - that's another  
subtask. I'll move on to that next, while I'm waiting for a review.  
Once someone has a look at it and suggests improvements, I'll commit it.

-- 
Anastasia Cheetham                   a.cheetham at utoronto.ca
Software Designer, Fluid Project    http://fluidproject.org
Adaptive Technology Resource Centre / University of Toronto