Move V2 documentation into "/v2" to prep for centralizing doc site

* Both V1 and V2 API documentation will exist as in this repository to
  make compilation and publishing easier.
  * V1 documentation will reside in "/" (for now)
  * V2 documentation will reside in "/v2" (for now)
* Moved all API V2 content into `v2/` subdirectory
* Created a specific compilation rule that uses the new `v2` layout
* Created a barebones layout for any markdown files that haven't been
  moved into v2
Migrate API V1 documentation to nanoc, keep in v1, render to root

* Separating the documentation into clear `v1` and `v2` directories
  makes maintenance easier
* Had to convert jekyll-based markdown to nanoc/kramdown processing,
  which had some challenges
  * Needed to write helpers to properly wrap code blocks, since the
    examples were just pasted into the markdown (not into ruby objects
    that are converted)
    * This is done because some of the examples have comments, and to
      JFSI.
    * XML examples had to be copied from the HTML output, since the
      `<` and `>` needed to be escaped.
* also updated the freckle logo to use the SVG version, for retina
  goodness.
Merge branch 'alpha' of github.com:cheerful/freckle-apidocs into alpha

Conflicts:
	Rules
	layouts/v2.html