upgraded nokogiri to 1.6 & replaced lambda with new expect syntax

Hey,friend
we should use 1.6 version of nokigiri ,because it's better and is also the dependency of many other gems for now... :)
And, I noticed the deprecated warning , so I replaced lambda with expect syntax in our test specs.

BTW, we do need one release ,because the official 0.7.0 is still using the old and buggy haricot which caused some problems here.

Thanks!