Add implicit defaults to DEFAULTS
Remove short-circuits from Site
move template site to default markdown renderer
Merge pull request #962 from dracula2000/refactor-site

Move defaults found in site.rb to DEFAULTS Hash
Merge pull request #961 from benbalter/default-markdown-engine

Move template site to default markdown renderer
Update history to reflect merge of #961
Update quickstart instructions with `new` command

Quickstart instructions as written would serve an empty directory.

They instruct the user to install Jekyll (:metal), `cd` to a directory that may not exist, and then run `jekyll serve` (:hurtrealbad:).

Instead, lets have them run `jekyll new` to stand up a scaffold site, so they can see how things work and poke around a bit.

It's one more command, but IMHO a better user experience for someone just getting started.
Merge pull request #966 from benbalter/quick-start-scaffold

Update quickstart instructions with `new` command
Update history to reflect merge of #966
Update history to reflect merge of #956
Update history to reflect addition of docs for page.path #951