[Feature] Replace patterns in subject

The subject supports now a DSL-setter to replace specific patterns from the execution output instead of paths only.

/c @AliSoftware @segiddins
No, there is no reason. I still have `ruby-1.8.7` in the build matrix. Because I didn't want to drop the support just for that, so I changed the pinned version to downgrade to the older version and accidentally comitted this dependency. Thanks for pointing out. :)