Always use sinatra from master until it is released

This should help avoid some confusion about the failing build

sinatra-contrib/.travis.yml

@@ -18,13 +18,11 @@ matrix:
     - { rvm: 2.3.1, env: tilt=master    }
     - { rvm: ruby-head, env: tilt=master    }
     - { rvm: 2.3.1, env: rack=master    }
-    - { rvm: 2.3.1, env: sinatra=master }
   allow_failures:
     - env: tilt=master
     - rvm: ruby-head
     - rvm: jruby-head
     - rvm: rbx
-    - env: sinatra=master
     - env: rack=master
 
 notifications:

sinatra-contrib/Gemfile

@@ -2,6 +2,7 @@ source "https://rubygems.org" unless ENV['QUICK']
 gemspec
 
 gem 'mustermann', github: 'sinatra/mustermann'
+gem 'sinatra', github: 'sinatra/sinatra'
 
 group :development, :test do