Depend on same tilt version as sinatra proper

We had to add some of template engines as development dependencies to get the
tests to pass, as of rtomayko/tilt@c86054abf8

/cc @judofyr

sinatra-contrib/lib/sinatra/respond_with.rb

@@ -174,7 +174,11 @@ module Sinatra
         end
         possible.each do |engine, template|
           # not exactly like Tilt[engine], but does not trigger a require
-          klass = Tilt.mappings[Tilt.normalize(engine)].first
+          if Tilt.respond_to?(:mappings)
+            klass = Tilt.mappings[Tilt.normalize(engine)].first
+          else
+            klass = Tilt[engine]
+          end
           find_template(settings.views, template, klass) do |file|
             next unless File.exist? file
             return settings.rendering_method(engine) << template.to_sym

sinatra-contrib/sinatra-contrib.gemspec

@@ -188,7 +188,7 @@ Gem::Specification.new do |s|
 
   s.add_dependency "sinatra",   "~> 1.4.0"
   s.add_dependency "backports", ">= 2.0"
-  s.add_dependency "tilt",      "~> 1.3"
+  s.add_dependency "tilt",      ">= 1.3", "< 3"
   s.add_dependency "rack-test"
   s.add_dependency "rack-protection"
   s.add_dependency "multi_json"
@@ -197,5 +197,19 @@ Gem::Specification.new do |s|
   s.add_development_dependency "haml"
   s.add_development_dependency "erubis"
   s.add_development_dependency "slim"
+  s.add_development_dependency "less"
+  s.add_development_dependency "sass"
+  s.add_development_dependency "therubyracer"
+  s.add_development_dependency "builder"
+  s.add_development_dependency "liquid"
+  s.add_development_dependency "redcarpet"
+  s.add_development_dependency "RedCloth"
+  s.add_development_dependency "asciidoctor"
+  s.add_development_dependency "radius"
+  s.add_development_dependency "coffee-script"
+  s.add_development_dependency "nokogiri"
+  s.add_development_dependency "creole"
+  s.add_development_dependency "wikicloth"
+  s.add_development_dependency "markaby"
   s.add_development_dependency "rake"
 end