Rename RefererManager to ReferrerManager?

[Glen Mazza]

Hi, I'd like to implement 
https://issues.apache.org/jira/browse/ROL-1229, on at least 5.1 
(possibly 5.0.2 as well).  Any critical backwards compatibility problems 
if I do so?  Another alternative is to close this issue as a "Won't 
Fix".  (As "referer" is an HTTP term: 
http://en.wikipedia.org/wiki/HTTP_referer#Origin_of_the_term_referer, 
misspelled or not.)

Thanks,
Glen