Bringing Accept header parsing in line with the spec.

For reference:
  http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.1
  http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2
Ensuring that generated Content-Type headers properly escape params.
Exposing Accept header parameters.
Simplifying regular expression to silence warnings.
Explicitly set falsy values for :template should not render a template
chat example: .live is removed in latest jquery, use .submit
Default host to localhost when in development mode.

* Running Rack apps on 0.0.0.0 in development mode will allow malicious
  users on the local network (ex: Coffee Shop) to abuse or potentially
  exploit the app. Safer to default host to localhost when in development
  mode.
chat example: use .on instead of submit
Merge pull request #634 from postmodern/localhost_development

Default host to localhost when in development mode.
don't run rdiscount tests on 1.9.2
Merge branch 'master' of github.com:sinatra/sinatra
lock to rdoc 1.x for now
fix rdoc version
run against 2.0.0 on travis
Fix CALLERS_TO_IGNORE to ignore Rubygems 2.0.0 require definition file

- Fixes #642
Merge pull request #643 from udzura/master

Fix CALLERS_TO_IGNORE to ignore Rubygems 2.0.0 require definition file
Merge pull request #632 from mcfiredrill/chat-example-fix

chat example: .live is removed in latest jquery, use .submit
Syntax fix for private methods and parameters
Merge pull request #626 from pvande/improving-accept-headers

Improving Accept header handling
Merge pull request #628 from richo/bugs/falsy_layouts

Explicitly set falsy values for :template should not render a template