Fixing url backslashes and prettifying JSON

- path.join in windows seems to convert all fordslashes into backslashes
regulating to the system path structure.

- Prettifying all JSON
Added an exclude : [path/, ...] feature.

Grunt-tree doesn't support "Building the files object dynamically".
So in return excluding files was not available.

To exclude any directory or path, simply add an array of URIs:
options : {
exclude : ['css/style.css',
'img/',
'js/bootstrap/secret.js' ]
}

Note: All paths are relative to the "current directory" / "cwd"
UNC paths / Prettify are now optional.

- Patched backslashes (UNC paths) fix , so that format+ext is working
again.

- Made UNC paths optional. (Default is false.)
UNC paths form backlashes in windows and fordslashes on linux.

- Prettify is now optional. (Default is false.)
Identical names don't override with format off

- {Format : false} made files with identical naming, across directories,
override one another. Simple patch
Merge pull request #3 from toxinhead/master

URL backslash fix + Prettifying JSON + Exclude paths