New system property to give control over how FrontBase plugin handles "contains"

Default has always been as a "like" operator but this can make it now like an existence check in a too many relationship.

Signed-off-by: Aaron Rosenzweig <aaron@chatnbike.com>
Merge pull request #375 from recurve/FrontbasePlugin

New system property to give control over how FrontBase plugin handles "c...