Improvements to the Android parser

Generally these commits add handling for new tags from PR #162.

- Handle AUTOLINK (#124)
- Handle BLOCK_CODE
- Handle ordered LISTs (#161)
- Handle HRULE (#140)
- Handle IMAGE (#149). Uses the same pattern as [Html.ImageGetter](http://developer.android.com/reference/android/text/Html.ImageGetter.html).

I know very little about iOS so it's probably best that someone else handles these tags on that platform. :)

- Fixed some of the newline logic for some more complex situations (60036b8)
- Fixed how quote blocks work (efbebdd). They were flying all over the place if you had a quote block w/ nested quotes, lists, or code blocks.