Add ConfigurationError exception class
Throw ConfigurationError on problems with loading config

Try to improve error handling. #172
Update tests to check for Configuration Error
Catch KeyboardInterrupt when serving
Remove unused imports
Remove pass in ConfigurationExpection
Reduce noise when configuration has error
Implement #86: Parse dir with - on command line
Merge pull request #176 from ngzhian/error-handling-output

Improve error handling
Merge pull request #182 from ngzhian/arg-to-option

Implement #86: Parse dir with - on command line