#24 Basic functional 'djconvert up' without arg parsing
#24 Test infrastructure
#24 Fix some issues in test infrastructure
#24 Use correct error msg and print usage for no_args
Add tests for 'up' with insufficient args
#24 Error for unknown subcommand
#24 Error if input file does not exist
#24 Add test for when output file doesn't already exist
#24 Add test for when output file should be overwritten
#24 Ensure command line filenames are actually used
#24 Add support for pretty output
Close #24: For now, no 'down' subcommand