Add stack trace to bin error output.

On the command-line, it is currently rather difficult to discover where/why an error is being generated as the output error message does not include a trace trace. Perhaps this was included at some point in the past and has disappeared with security changes to the Error object. Current error messages can originate deep inside the module hierarchy and/or not be easily greppable due to generic/concatenated messages.

### Example Output

#### Before
```
> ./bin/cmd.js -t ./test/bin_tr_error/tr.js ./test/bin_tr_error/main.js
Error: there was error
>
```

#### After
```bash
> ./bin/cmd.js -t ./test/bin_tr_error/tr.js ./test/bin_tr_error/main.js
Error: there was error
    at Stream.end (/Users/timoxley/Projects/libs/node-browserify/test/bin_tr_error/tr.js:9:28)
    at _end (/Users/timoxley/Projects/libs/node-browserify/node_modules/through/index.js:65:9)
    at Stream.stream.end (/Users/timoxley/Projects/libs/node-browserify/node_modules/through/index.js:74:5)
    at f (/Users/timoxley/Projects/libs/node-browserify/node_modules/module-deps/index.js:230:19)
    at makeTransform (/Users/timoxley/Projects/libs/node-browserify/node_modules/module-deps/index.js:296:20)
    at ap (/Users/timoxley/Projects/libs/node-browserify/node_modules/module-deps/index.js:215:13)
    at applyTransforms (/Users/timoxley/Projects/libs/node-browserify/node_modules/module-deps/index.js:232:11)
    at /Users/timoxley/Projects/libs/node-browserify/node_modules/module-deps/index.js:178:17
    at fs.js:266:14
    at Object.oncomplete (fs.js:107:15)
>
```

amended: fixed some 2 space indentation.