Improve message for property format linter

Changes the lint error description for the property format linter to
suggest that the user is missing a semi-colon, as that usually is the
reason they are seeing the lint, and the more general language of the
error can be confusing the read at times.

Change-Id: I58dcb2845ba206e42de444381ab77d8bd1503614
Reviewed-on: https://gerrit.causes.com/17772
Tested-by: Shane da Silva <shane@causes.com>
Reviewed-by: Joe Lencioni <joe.lencioni@causes.com>