Adds --verbose output

As updated in the `readme.md` 


### Troubleshooting

The tradeoff of a neatly organized Grunt configuration is sometimes having trouble locating which file is declaring exactly what.

In that case, or if loading some file is causing an error and aborting your Grunt process, you can always run:

```shell
grunt --verbose
```

A nice log of processed files and loaded tasks/targets will help you locate the problems. Here's the output when running
on this very repo:


```
Loading grunt configs via "load-grunt-configs" from 6 file(s).
Loading config/connect.js...is fn(), invoking...OK
+ connect: [options, docs]

Loading config/jshint.json...OK
+ jshint: [options, lib, build, test]

Loading config/watch.js...is fn(), invoking...OK
+ watch: [lib, build, test, docs, livereload]

Loading config/clean.coffee...is fn(), invoking...OK
+ clean: [config, tmp]

Loading config/nodeunit.yml...OK
+ nodeunit: [load_grunt_configs]

Loading config/markdown.cson...OK
+ markdown: [docs]

```