Support Gemspec groups, briefly.

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    appraisal (0.3.7)
+    appraisal (0.3.8)
       bundler
       rake
 

features/appraisals.feature

@@ -8,6 +8,9 @@ Feature: run a rake task through several appraisals
     source "http://rubygems.org"
     gem "rake", "0.8.7"
     gem "factory_girl"
+    group :assets do
+      gem 'sass-rails', "  ~> 3.1.0"
+    end
     """
     When I add "appraisal" from this project as a dependency
     And I write to "Appraisals" with:

lib/appraisal/gemfile.rb

@@ -22,6 +22,10 @@ def gem(name, *requirements)
       @dependencies[name] = Dependency.new(name, requirements)
     end
 
+    def group(name)
+      # ignore the group
+    end
+
     def source(source)
       @source = source
     end