Fixed blog_url not returning & rake setup_github_pages failing

When executing `rake setup_github_pages`, an error tells that `url` don't exist. The reference to that variable has been changed to a call to `blog_url`.

The function `blog_url` was not returning anything, failing to properly write the `_config.yml` file. It now does return what should have.
Fixed blog_url when user contains uppercase letters
Made blog_url becalled just once...

...and stored in the `url` variable.
Merge pull request #1331 from Darkhogg/patch-1

Fixed setup_github_pages failing and not properly writing url to _config.yml
Fix README to be more inline with my style

and remove stuff that is superfluous to my site.
Personalize _config.yml
Ignore the .ruby-version file
Add twitter and github info
Use .md instead of .markdown
Add basic theme
Add content from old site
Add trace build target
Replace default favicon with my ugly one
Fix post_url not working correctly
Setup for deploy to github pages
Add blog post about flaskr docs troubles
Fix my keybase proof being removed by Jekyll
Write up a rough synopsis of my week
Write lots mores
Increase all headings one level