add redcarpet gem to Gemfile
README some small fixes
update German Readme
Merge pull request #669 from burningTyger/master

update German Readme and some small English Readme fixes
Merge branch 'master' of github.com:sinatra/sinatra

Conflicts:
	Gemfile
server can have different defaults now
update Requirement section
fix markup
fix section hierarchy in readme
update list of http methods
make AcceptEntry behave like string
fix test for Ruby 2.0
avoid test name collision
avoid to_enum warning on 2.0