Adds some improvements in Open Graph

Adds the following tags in open-graph: og:site_name,
article:published_time, article:section and article:tag
Pygments frenzy!

Now it's possible to choose any existing Pygments style that you want!
By the time I'm writing this these are all the available styles:
autumn, borland, bw, colorful, default, emacs, friendly, fruity, manni,
monokai, murphy, native, pastie, perldoc, rrt, solarizeddark,
solarizedlight, tango, trac, vim and vs. Also this commits removes the
statically coded background for highlighted code and lets the respective
pygment .css file take care of it. Also, by default, it will use
native.css style, the same used before this change.
rrt.css is too ugly and don't deserve to be commited
Minor documentation fixes and improvements.
Reword CUSTOM_CSS doc for clarity.
Small grammatical fix.
Keeps original bootstrap borders

Removed the borders tweaks in `.highlight pre` and `.linenodiv pre` and the custom `border-right`in `.linenodiv pre`.
Merge pull request #57 from hlapp/doc-fixes

Minor documentation fixes and improvements.
Some more README consistency
Changes the way the pygments css are generated

Now the we're generated using ".highlight pre".
Added the pygments styles to README.md

Documented these changes in the README.md
Merge branch 'pygments-frenzy' of https://github.com/magnunleno/boothack into magnunleno-pygments-frenzy

* 'pygments-frenzy' of https://github.com/magnunleno/boothack:
  Added the pygments styles to README.md
  Changes the way the pygments css are generated
  Keeps original bootstrap borders
  rrt.css is too ugly and don't deserve to be commited
  Pygments frenzy!

Conflicts:
	README.md
	static/css/style.css
Fixed language in README
Updated screenshots
Adds inline tags (tagcloud)

Setting DISPLAY_TAGS_INLINE = True will cause the theme to render all tags
inline in the sidebar.
Adds basic authors and author page
Add twittertimeline widget
add span class icon-label to twitter_timeline
Include instructions for twitter-timeline feature
Fix tag styles; add tag-0, de-duplicate tag-2.

There was no style for tag-0. There were two definitions for tag-2.