Fix StorageObject#metadata for 1.9.2

In ruby 1.8.7, Array#to_s behaves like:

>> ['a',1,'b',2].to_s
=> "a1b2"

In ruby 1.9.2 however:

>> ['a',1,'b',2].to_s
=> "["a", 1, "b", 2]"

This means that StorageObject#metadata is returning mangled values for those headers. This fix should replicate the 1.8.7 behavior in 1.9.2. 

Tests are included and pass (for that specific test) in both 1.8.7 and 1.9.2

lib/cloudfiles/storage_object.rb

@@ -45,7 +45,12 @@ def object_metadata
         response = self.container.connection.cfreq("HEAD", @storagehost, @storagepath, @storageport, @storagescheme)
         raise CloudFiles::Exception::NoSuchObject, "Object #{@name} does not exist" unless (response.code =~ /^20/)
         resphash = {}
-        response.to_hash.select { |k,v| k.match(/^x-object-meta/) }.each { |x| resphash[x[0]] = x[1].to_s }
+        metas = response.to_hash.select { |k,v| k.match(/^x-object-meta/) }
+
+        metas.each do |x,y|
+          resphash[x] = (y.respond_to?(:join) ? y.join('') : y.to_s)
+        end
+
         {
           :manifest => response["x-object-manifest"],
           :bytes => response["content-length"],

test/cloudfiles_storage_object_test.rb

@@ -109,12 +109,12 @@ def test_set_metadata_fails
 
   def test_read_metadata_succeeds
     connection = stub(:storagehost => 'test.storage.example', :storagepath => '/dummy/path', :storageport => 443, :storagescheme => 'https', :cdnmgmthost => 'cdm.test.example', :cdnmgmtpath => '/dummy/path', :cdnmgmtport => 443, :cdnmgmtscheme => 'https', :cdn_available? => true)
-    response = {'x-container-bytes-used' => '42', 'x-container-object-count' => '5', 'x-object-meta-foo' => 'Bar', 'last-modified' => Time.now.to_s}
+    response = {'x-container-bytes-used' => '42', 'x-container-object-count' => '5', 'x-object-meta-foo' => 'Bar', 'x-object-meta-spam' => ['peanut', 'butter'], 'last-modified' => Time.now.to_s}
     response.stubs(:code).returns('204')
     connection.stubs(:cfreq => response)
     container = CloudFiles::Container.new(connection, 'test_container')
     @object = CloudFiles::StorageObject.new(container, 'test_object')
-    assert_equal @object.metadata, {'foo' => 'Bar'}
+    assert_equal @object.metadata, {'foo' => 'Bar', 'spam' => 'peanutbutter'}
   end
 
   def test_write_succeeds