allow a format :plain option

Signed-off-by: John Nunemaker <nunemaker@gmail.com>

lib/httparty.rb

@@ -18,7 +18,8 @@ module HTTParty
     'text/javascript'        => :json,
     'text/html'              => :html,
     'application/x-yaml'     => :yaml,
-    'text/yaml'              => :yaml
+    'text/yaml'              => :yaml,
+    'text/plain'             => :plain
   } unless defined?(AllowedFormats)
   
   def self.included(base)

spec/httparty_spec.rb

@@ -149,6 +149,11 @@ describe HTTParty do
       @klass.default_options[:format].should == :yaml
     end
     
+    it "should allow plain" do
+      @klass.format :plain
+      @klass.default_options[:format].should == :plain
+    end
+    
     it 'should not allow funky format' do
       lambda do
         @klass.format :foobar