New Project Template improvements

[hmans]

Things we should add to the new project template:

• [x] a binstub for flutterby
• [x] change date of generated blog post to today
• [ ] an RSS feed for the blog section
• [ ] an index for the blog section
• [ ] change templates to ERB, not Slim, in preparation for removing Slim as a Flutterby dependency
• [x] add a sample Rakefile with a deploy task (and a bin/rake binstub)