[FIX] Make route parsing regex more robust

- fixes sinatra/sinatra/#611
- adds support for case-insensitive URL encoding
[FIX] Support ruby 1.8 in routing regex
Rewrite the french README in Markdown
default response content type to html even with newest rack
unloadable library might raise NameError in tilt master
do not call super in Response#finish to avoid infinite loop or body proxy
make sure we support escaped new lines, closes #568
disable wlang on rbx in 1.8 mode, too
rbx-19mode is segfaulting on travis
rubinius is segfaulting
convert README.de to markdown
fix broken links in README.md
remove 1.8 -rubygems cli argument from READMEs
remove German rdoc README

It was replaced with a markdown version of it in fe258f2
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
code typo in streaming example in README