Spliting the GUI Toolkits page in two

One for the Toolkit list and other for the Guide to choose a toolkit.
Fixing a URL
Merge http://github.com/mono/website into gh-pages

Conflicts:
	docs/gui/gui-toolkits.md
Applying pull request's corrections
Merge pull request #66 from thiagoabreu/gh-pages

Gui Toolkits