Fix for CSSRuleset and few new features

Could someone review share some comments ?

html5lib - 0.999
pyPdf2 - 1.20
Pillow - 2.3.0
reportlab - 2.7 (and 3.0)
six - 1.5.2

1) The main thing here is that it should entirely fix issues #126 and #69 as the w3c.css.CSSDefinitions class has been rewritten to be indexed dict rather than dict, tested be specifying code and running it 200 times
```
<html>
<head>
<style>
    .my_class {
        border: 1pt solid red;
    }
    .my_class {
        border: 1pt solid blue;
    }
</style>
</head>
<body>
<div class="my_class"></div>
</body>
```

2) The default behavior for &lt;ul&gt; has been changed as per html spec. The bullet points use list-style-position: "outside" as default value and move the bullet point -15 points
3) Ability to set th/td heights has been added to force the height of cells
4) Ability to set an offset on the pagenumber tag with ability to set one on pagecount coming shortly