Add and/or fix guards to that specs run correctly without tilt installed

spec/plugin/additional_render_engines_spec.rb

@@ -1,5 +1,13 @@
 require_relative "../spec_helper"
 
+begin
+  require 'tilt'
+  require 'tilt/erb'
+  require 'tilt/string'
+  require_relative '../../lib/roda/plugins/render'
+rescue LoadError
+  warn "tilt not installed, skipping render plugin test"  
+else
 describe "additional_render_engines plugin" do 
   it "supports additional render engines" do
     app(:bare) do
@@ -18,3 +26,4 @@
     proc{body('/nonexistent')}.must_raise Errno::ENOENT
   end
 end
+end

spec/plugin/additional_view_directories_spec.rb

@@ -1,5 +1,13 @@
 require_relative "../spec_helper"
 
+begin
+  require 'tilt'
+  require 'tilt/erb'
+  require 'tilt/string'
+  require_relative '../../lib/roda/plugins/render'
+rescue LoadError
+  warn "tilt not installed, skipping render plugin test"  
+else
 describe "additional_view_directories plugin" do 
   it "supports additional view directories" do
     app(:bare) do
@@ -41,3 +49,4 @@
     app.render_opts[:allowed_paths].must_equal expected
   end
 end
+end

spec/plugin/content_for_spec.rb

@@ -83,7 +83,6 @@
     body.strip.must_equal "bar foobaz"
   end
 end
-end
 
 describe "content_for plugin with mixed template engines" do
   before do
@@ -130,3 +129,4 @@
     body('/a').strip.must_equal "bar\nfoo"
   end
 end
+end