Dmgutils

[clburlison]

This works and is quite helpful for a project I'm working on right now.

I'd like some feedback on the following areas:

1. dmgutils okay for name?
2. Since this requires "github.com/groob/plist" should I add a Gopkg.toml file to the root directory?
3. One thing that I've found helpful is a function to check the mountpath and return a file listing. Would you suggest including the snippet below or is that getting to custom for a library?

   // checkExt - Check a directory for files with a specific extension;
   // return a listing of files found.
   func checkExt(ext string, path string) []string {
       var files []string
       filepath.Walk(path, func(path string, f os.FileInfo, _ error) error {
           if !f.IsDir() {
               r, err := regexp.MatchString(ext, f.Name())
               if err == nil && r {
                   files = append(files, f.Name())
               }
           }
           return nil
       })
       return files
   }

4. Testing? Besides including a small dmg file in the repo, doing a mount, then unmount I'm not sure how else I could add a valid test case.

[groob]

I should probably stress out in the README that this whole repo is for testing ideas and you'd be mad to import this repo into another project. Copy/Paste the code into a real project is better.

having said that, thanks for contributing something useful! I think adding a Gopkg would be great, but can be done in a followup PR. I'm going to merge this now!