Support StrokeStyle

I modified some codes in azure to support StrokeStyle like cap-style, join-style and some others. But there are some problems.
First of them, It doesn't look the join-style works well. I tested it join-style bits beside cap-style in C. It looks 21(cap,join) as hex in C. So as you can see in code, I implemented set method in azure_hl. I think the bit is set properly but the only join_style isn't applied that I want.(I tested CAP_BUTT and CAP_ROUND. Both of them work fine. )
Second, I will send PR  about border-style after this is merged. I can render DashedBorderStyle but can't render DottedBorderStyle as I expect. Because I supposed servo and firefox uses same graphic engine. So  I refered to firefox code(link : http://mxr.mozilla.org/mozilla-central/source/layout/base/nsCSSRenderingBorders.cpp#1080) to render them properly specially for DashPattern and cap, join style.
If you can catch what thoes problem are, let me know that I will fix it before it's merged. But I think second one is you might catch after I send main codes for border-style.