rogerhutchings/img2iss — pull request #6 by rogerhutchings (2014-06-03 13:16:26+00:00)
Title: Show usage when called without required args

Instead of this error:

```bash
henry@henry-pc: img2iss (master=): which img2iss
/usr/bin/img2iss
henry@henry-pc: img2iss (master=): img2iss

fs.js:427
return binding.open(pathModule._makeLong(path), stringToFlags(flags), mode);
^
Error: ENOENT, no such file or directory '/home/henry/Code/img2iss/lib/../config/config.json'
at Object.fs.openSync (fs.js:427:18)
at Object.fs.writeFileSync (fs.js:966:15)
at Object.module.exports.initialise (/home/henry/Code/img2iss/lib/config.js:47:20)
at module.exports (/home/henry/Code/img2iss/lib/img2iss.js:38:16)
at Object. (/home/henry/Code/img2iss/bin/img2iss:4:1)
at Module._compile (module.js:456:26)
at Object.Module._extensions..js (module.js:474:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:312:12)
at Function.Module.runMain (module.js:497:10)

```