Added the Tire::Configuration.pretty option for JSON output

* The option is set to `true` by default
* Pass a truthy value to set the option to "true" or false/nil or false/nil to set the option to "false"

lib/tire/configuration.rb

@@ -19,6 +19,14 @@ def self.logger(device=nil, options={})
       @logger || nil
     end
 
+    def self.pretty(value=nil, options={})
+      if value === false
+        return @pretty = false
+      else
+        @pretty.nil? ? true : @pretty
+      end
+    end
+
     def self.reset(*properties)
       reset_variables = properties.empty? ? instance_variables : instance_variables.map { |p| p.to_s} & \
                                                                  properties.map         { |p| "@#{p}" }

test/unit/configuration_test.rb

@@ -52,6 +52,16 @@ def teardown
         assert_instance_of Tire::Logger, Configuration.logger
       end
 
+      should "set pretty option to true by default" do
+        assert_not_nil Configuration.pretty
+        assert Configuration.pretty, "Should be true, but is: #{Configuration.pretty.inspect}"
+      end
+
+      should "set the pretty option to false" do
+        Configuration.pretty(false)
+        assert ! Configuration.pretty, "Should be falsy, but is: #{Configuration.pretty.inspect}"
+      end
+
       should "allow to reset the configuration for specific property" do
         Configuration.url 'http://example.com'
         assert_equal      'http://example.com', Configuration.url