message length counter

![screen shot 2013-11-23 at 5 46 52 pm](https://f.cloud.github.com/assets/4720594/1607875/f5a112cc-54aa-11e3-8f9f-868bbf9444c7.png)
![screen shot 2013-11-23 at 5 48 49 pm](https://f.cloud.github.com/assets/4720594/1607876/fac05bc8-54aa-11e3-8154-7f44366853dd.png)

redo of this pr https://github.com/meatspaces/meatspace-chat/pull/101