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, this is a failing on the canvas text API. (Though fortunately, the API does the right thing...)

Newlines simply aren't supported by canvas text API so they are dropped, and treated as a space. The line just keeps on going... 

Wrapping text at newlines would be doable, but I think we should wait as this introduces a number of edge cases. New lines are also counter to the purpose of the label block, which is meant for short items. (The full text box feature which has been discussed should naturally support newlines). 

Since nothing breaks, I think the current behavior is fine. I'd like to keep this simple, especially because if we want RTL support (eventually we should!) then the cases and issues grow quickly.