Added new merge codes: #&#35FORMID#&#35, #&#35CONTENTPAGEID#&#35 , #&#35BLOGPOSTID#&#35, #&#35ATTRIBUTEID#&#35

Added new merge codes:

##FORMID## (contactform identifier)
##CONTENTPAGEID##
##BLOGPOSTID##
##ATTRIBUTEID##


Removed error that occurred when attempting to create a new entity whose generated custom url matched a previous entity or historic custom url already in the system. The new behavior results in the entity's identifier being appended to the end of the generated custom url when this situation occurs.
The custom url history for an entity can now be viewed by navigating to the "delete custom url history" page which is accessible from the "more actions" menu.