[markdown] Upgrade to tilt 2.0

Looking to support markdown and possibly textile processing-- so grab
the latest tilt.
[markdown] SlideMarkdown: Like markdown, but..

* Starts with a <section>, ends with a </section>

* hr delineates slides in reveal-ck, so close the current one and open
  up a new one: "</section><section>"

This commit supplies a quick approach to this.
[markdown] Distinguish "Embedded Markdown" from Markdown

Embedded Markdown is the content filter you can apply from within HAML.

Markdown will be what happens when you create a file that ends in ".md"
and run reveal-ck generate against it.
[markdown] reveal-ck generate and "slides.md"
[markdown] Markdown stuff now lives in "markdown/"
[markdown] CHANGELOG
Write slides in Markdown

* markdown-support:
  [markdown] CHANGELOG
  [markdown] Markdown stuff now lives in "markdown/"
  [markdown] reveal-ck generate and "slides.md"
  [markdown] Distinguish "Embedded Markdown" from Markdown
  [markdown] SlideMarkdown: Like markdown, but..
  [markdown] Upgrade to tilt 2.0
[generate] Add msg re: what file is being generated
[generate] CHANGELOG
Print basic message upon generation

* msg-for-generate:
  [generate] CHANGELOG
  [generate] Add msg re: what file is being generated
[serve] "reveal-ck serve" now starts web server
[serve] CHANGELOG
[serve] Match help output with regex

..So as not to be so brittle.
`reveal-ck serve`: Make content available via http

* serve:
  [serve] Match help output with regex
  [serve] CHANGELOG
  [serve] "reveal-ck serve" now starts web server
[textile] reveal-ck generate now supports textile

..via RedCloth and Tilt.
Write slides in Textile

* textile:
  [textile] reveal-ck generate now supports textile
[reveal.js] Updated Embedded reveal.js
Merge branch 'next-release'

* next-release:
  [reveal.js] Updated Embedded reveal.js
  [textile] reveal-ck generate now supports textile
  [serve] Match help output with regex
  [serve] CHANGELOG
  [serve] "reveal-ck serve" now starts web server
  [generate] CHANGELOG
  [generate] Add msg re: what file is being generated
  [markdown] CHANGELOG
  [markdown] Markdown stuff now lives in "markdown/"
  [markdown] reveal-ck generate and "slides.md"
  [markdown] Distinguish "Embedded Markdown" from Markdown
  [markdown] SlideMarkdown: Like markdown, but..
  [markdown] Upgrade to tilt 2.0
[v0.2.0]

+ Slides with Markdown
+ Slides with Textile
+ Webserver via `reveal-ck serve`