BS3: Remove Glyphicons

As of today, Glyphicons has moved out of Bootstrap 3 and into it's [own repository](https://github.com/twbs/bootstrap-glyphicons) under the [twbs organization](https://github.com/twbs), where Bootstrap 3 will reside when it launches as well. Moving the Glyphicons font into a separate project makes a lot of sense:

1. Makes Glyphicons more readily available to the masses, with or without Bootstrap's integration.
2. Keeps the core project as lean as possible with regards to number of files, build processes, versioning, and more.
3. Enables the community to more easily swap other icon libraries in and out.

**Glyphicons will continue to be the official Bootstrap icon font** and will be featured in the Bootstrap 3 documentation for easy access and implementation.

Head on over to [glyphicons.getbootstrap.com](http://glyphicons.getbootstrap.com) to check 'em out.