Package with Ruby 2.1

Previously, the Gemfile of the project assumed that all work was being
done against Ruby 1.9.x.  The CI tests ran successfully on the 2.1
line because they excluded the version-specific debug gems with a
--without debug.  The instructions (and indeed good user experience)
did not ask users to do this, so when bundle install was run in a
non-1.9 Ruby runtime, the gems would not install.

This change updates the Gemfile to install version-specific debug gems
allowing development against 1.9.x, 2.0.x, and 2.1.x.

Author: nebhale

Gemfile

@@ -14,6 +14,7 @@ group :development do
 end
 
 group :debug do
-  gem 'ruby-debug-base19x', '>= 0.11.30.pre'
   gem 'ruby-debug-ide'
+  gem 'ruby-debug-base19x', '>= 0.11.30.pre', :platforms => :ruby_19
+  gem 'debase', :platforms => [:ruby_20, :ruby_21]
 end

Gemfile.lock

@@ -7,9 +7,11 @@ GEM
       simplecov (>= 0.7.1, < 1.0.0)
     crack (0.4.2)
       safe_yaml (~> 1.0.0)
+    debase (0.0.9)
+      debugger-ruby_core_source
     debugger-ruby_core_source (1.3.5)
     diff-lcs (1.2.5)
-    docile (1.1.3)
+    docile (1.1.4)
     json (1.8.1)
     multi_json (1.10.1)
     parser (2.1.9)
@@ -28,7 +30,7 @@ GEM
     rspec-expectations (3.0.0)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.0.0)
-    rspec-mocks (3.0.0)
+    rspec-mocks (3.0.1)
       rspec-support (~> 3.0.0)
     rspec-support (3.0.0)
     rubocop (0.23.0)
@@ -62,6 +64,7 @@ PLATFORMS
 
 DEPENDENCIES
   codeclimate-test-reporter
+  debase
   rake
   redcarpet
   rspec