Htmlhelpers glyphs

Created html helpers package; please review and check if this is what you had in mind.

I've created the nuspec file and added it to the build script.
I also added this html helpers  package to the sample package (so that I could easily test with it).

Feedback is appreciated. Please look at the api

```html
<li>@Html.ActionLinkWithGlyphIcon(Url.Action("Index"),
                                    "Back to List",
                                    GlyphIcons.icon-list)</li>
```

and the location of the helpers folder.