Fix arguments of app.js

[AntoineGautier]

app.js

parser.addArgument(
  ['-p', '--prettyPrint'],
  {
    help: 'Pretty print JSON output. The -o/--output should be raw-json/json/cxf.',
    action: 'storeTrue'
  }
)

parser.js

const out = (prettyPrint === 'true') ? JSON.stringify(rawJson, null, 2) : JSON.stringify(rawJson)

This seems incorrect as prettyPrint will be interpreted as a Boolean, not a string.

app.js

parser.addArgument(
  ['-d', '--directory'],
  {
    help: 'Specify output directory, with the default being the current.',
    defaultValue: 'current'
  }
)

Why the string current is used for the current directory as opposed to . or ./?
This requires conversions such as:
lib/cxfExtractor.js

  if (directory === 'current') {
    directory = ''
  }

At least such conversions should be made once and for all in app.js and each function should rather use OS common pathnames.