Added the definition for kbd in poole.css

Useful tag to typeset keyboard keys.
Improve the 'First Post'

Also add the .gitignore file to ignore the '_site' folder.
Changed the tittle of the blog
Add instructions on how to run jekyll locally
Move the kbd tag definition to my_additions.css

It was previously in the poole.css file, but put new tags in a the new
my_additions.css file is better than changing the css file that comes
with poole.
Add the post about Using Ebib as a draft
Improved kbd tag appearance in the css file.
Update the "first post" and publish the Ebib post

The "first post" was also updated, including instructions on how to
setup Jekyll.

The post about using Ebib to manager BibTeX files was published (moved
from _drafts to _posts and renamed to have a proper date).