Initial commit.

Initial commit of files generated by `jekyll new`.
Add "Error 404" page.
Update Jekyll config file to ignore 'vendor'.

Quote from http://bit.ly/16VB2Yf (read the article for more info):

"When Heroku builds the application slug, it installs gems into the
vendor directory. This can cause some strange results, most commonly
Jekyll test posts showing up as published. The fix is, simply, to
exclude the vendor directory in your _config.yml."
Add Gemfile.
Add Rakefile.
Add Rackup file.
Add Procfile.