Changed top navigation bar.

* Removed pages from top bar.
* Added social icons to that bar.
Changed footer.

* Removed social links.
* Added pages links.
Google Analitycs own file.

Google Analitycs code was removed from head template and added
to a different file from where it is included.
Added font-awesome.

Font-awesome added to the project, required to include a new css
reference, some font files and css directory was moved to a new assets
directory.
Added archive page with all posts.
New config variables in _config.yml.

* Added social profiles links.
* Added exclude options.
* Reorganization of the file.
Added tag system.

* Added default tag for untagged posts.
* Added post author link in post layout.
* Added post tags in post layout.
* Adedd tag layout.
* Added tag plugin.
Archive's title and RSS link in index.

* Added Archive title in archive page.
* Removed RSS link in index.html (added at header).
Styling changes.