Fix rule execution

* Rectified the regex for the "contains" operator to use java.util.regex.Pattern#find()
instead of String#matches. The latter does a pattern comparison of the input against
the subject but the former searches for the pattern.

* The rules map in RulesRegistry was using the rule ID to store the rules instead of
using the river ID

* Set the source property of the drop to "rules" before its put on the publish queue

* Added missing dependencies for boilerpipe