add yml file stat() functionality, in case dictionary file has changed
raise error on invalid dictionary during register, warn and continue while running
invalid dictionary refactoring per @electrical and @jordansissel
deprecate and link to other filters
Merge pull request #975 from kurtado/yamlstat

add yml file stat() functionality, in case dictionary file has changed
Merge pull request #983 from kurtado/doc/filter/grep

deprecate and link to other filters
Merge git://github.com/logstash/logstash