Label block

This replaces #362  and makes the text block a very simple label text block. 

It takes in a string, and a font size (in point values). 

It will:
* Rotate text with the sprite
* Move text to the end of the word
* Draws text at alphabetic baseline
* Always stamp LTR. There will need to be a bit of work done for RTL.

Example:
![screen shot 2014-06-29 at 10 22 34 am](https://cloud.githubusercontent.com/assets/1505907/3423921/a02170cc-ffb2-11e3-9d27-0bd111a033d5.png)

So, you've convinced me about the line drawing. (And I do agree, it's just about picking a metaphor.) However, I still feel that the connection to the pen size isn't very apparent. Especially if most browsers have a minimum size. That means pen sizes 1-6 (or whatever) look identical when stamping text, but beyond that, the text looks different. This, I think, is pretty confusing. 

I'm fine with it being drawn in px, but then to draw a reasonable text size, I'd need to make the pen ~14, but that would be an unreasonable line size for most uses.