merging title fix from Michael Hackett
Add slide backgrounds

Munged in from:

* https://github.com/jacobo/showoff/commit/e1af36ff12e285382d2cf3ccaf08de9dbdd48550
* https://github.com/jacobo/showoff/commit/66d7d69fb510ccbd12196526a509d57d2774651d
Add Disney HTML5 Polyfills presentation to the real world usage section.

Conflicts:
	README.rdoc
Adding syntax highlighting for gherkin.
Add Kramdown support

Fixes #188.
Update docs with Kramdown support
Merge pull request #182 from russellb/patch-1

Fix a typo in a comment. s/customr/custom/
Merge pull request #183 from jcoglan/master

Running under nginx+passenger throws an encoding error
Conflicts:
	lib/showoff.rb
Restored disabled markup-engine configuration (ref: 616bf52).

It's not clear to me why this line was commented out, as the commit message says only "whitespace", referring to the removal of extraneous white space from another part of the file. Was it an accident? (e.g., commented out for testing and checked in unintentionally)
Added support for passing options hash from showoff config file to rendering engine via Tilt.

Previously, some options were handled manually for the Maruku engine, but not for any of the others. The markdown engine wrappers in Tilt allow the passing of options to the various libraries through a hash given with the renderer is instantiated. The special handling in Showoff for the Maruku engine have been left unchanged for now, but it might be possible to migrate the code to use the same mechanism in the future. (I haven't used Maruku yet myself, so I didn't want to mess with the config code.)

Conflicts:
	lib/showoff.rb
For the markup engine config settings, hash keys are converted from strings to symbols.

The Tilt markup engine wrappers expect hash keys that are symbols, and there is no way to specify hashes in that format in JSON. But there's no reason the existing Maruku engine settings code couldn't be tweaked to expect symbol keys and work the same way.
Fixes exception when no renderer options specified.

(Oops! Forgot to test with example presentation.)
Added markdown option docs and fixed defaults

The code loading markdown options omitted the defaults passed in. This
commit restores it. It also adds documentation of the new feature.
Document the slide background feature
Bump version
Merge pull request #112 from binford2k/wip/merge_upstream

Wip/merge upstream