Add New Snippet Page
Add Snippet Detail and CSS

* Add mezzpaste.css, a trimmed down version of the dpaste CSS.
* Add base.html to override the dpaste/base.html template, linking in
  mezzpaste.css.
* Add a template to override the Snippet Pre template.
* Add a template to override the Snippet Details page, integrating it
  into Mezzanine and Bootstrap3.

* Modify the New Snippet template to use the dpaste/base.html template.

* Remove CSS Styles and the Shortcuts text from the Snippet Form
  template.
Add Top Languages Right Panel

* Add the mezzpaste_stats tag to return a list of the most used lexers.
* Add the lexer_display_name filter to return the Display Name of a
  lexer.
* Add the stats_panel.html template to render the most used lexers.

* Modify the dpaste/base.html template to include the stats_panel.html
  template.