Add a `-r`,`--recursive` option to `CLI::FileProcessorCommand`

[postmodern]

Add a -r, --recursive option to CLI::FileProcessorCommand. It should allow giving directory paths as arguments, in addition to file arguments, and recursively processing each file in each directory. This will automatically add the -r,--recursive option to every command which inherits from FileProcessorCommand.

[postmodern]

Should we even have a -r option, or should ronin grep, etc, behave recursively by default if you give it a directory?