Immersity site redesigned with agency-jekyll-theme

Updates _site cache.
Updates the blog section.
- Now it's posible to create post and these are going to appear on blog sections immediately.
- To write a post you have to: create a file on the dir _post with a name accordind this format: YEAR-MONTH-DAY-title.MARKUP. Example: 2014-11-15-new-post.md
Updates the site.
- About section is replaced by blog and moved to end of page (just
  before contact)
- New section about us is created which contains the immersity video.
- The Privacy Policy and Terms links were removed.
- Change the background image.
- Change the color font on welcome text.
- Tell me more button now goes to the video section.
- Contact form cleanup (and indentation).
- Implements contact form via brace forms.
- Remove unused layouts.
- Remove unused pages.
- Clean up _config.yml.
- Remove includes not being used.
- Rename everything regarding portfolio and portfolio_grid with blog
- Remove images not being used.
- Remove unnecessary js files
- Improves fonts and backgroud image.
- Removes trailing spaces.
- Renames to map-bg for consistency.
- Renamed #portfolioModal to #post.
- Wrote an actual _layout/default template (uses {{ content }}).
- Fixed index to use the new layout.
- Removes layout from the post since it opens as a modal.
- Deletes and updates text displayed in the page.
- Rearranges the style inclusions to avoid confusion.
Removes execution access to stylesheet.
Removes yet another level of indirection.
Now the resources are organized more cleanly:
- _includes: only has html partials.
- _layouts: has only used layouts.
- css: has all css files.
- img: has all img files.
- js: has all javascript files.
Added support for multiple languages.
- Language is selected in the property site.lang.
- Currently supports spanish ("sp") and english ("en").
- Changed default language to spanish.
- Added link to youtube video with subtitles.
Updated social networks.
- Only left github, linkedin and twitter links to contact team members.
- Added social networks for immersity itself.
- Made consistent the order in which social networks are displayed.
Modified .gitignore to ignore cache and .DS_Store files, and the _site dir.
Adds first blog post with custom image (post is in spanish, dummy post
for english version)