add namespace document at manipulating
Merge pull request #83 from yodalee/issue12

add namespace document at manipulating
fix issue 3

origin empty condition is count(child::*) = 0
which will allow tag with text in it pass
like <div>aaaa</div>

New condition is not(node()), solve this problem
update unittest for empty test in issue3
update function comment is cssselectpatch, doc
Merge pull request #82 from yodalee/issue3

fix issue 3
add attribute select intro. in doc