Use OptionParser (closes #7).

* Supports -h and --help options.
* Rescue OptionParser::ParseErrors and re-raise them as CLI::Errors.
* Moved CLIParser::EXIT_FAILURE, EXIT_SUCCESS and Error into CLI.
* Removed CLIParser.
Merge remote-tracking branch 'postmodern/optparse'
Use whitespace after comma
Sync devtools
Use communicative variable name
Adjust flay score
Adjust reek config