Add options for setting custom typeface for accent texts and custom text for floating label

As the title says, covers the features discussed in both #21 and #13.

* Custom font setting for what I'm calling "accent text", referring to any text drawn with the `paint` field . This is text like the floating label, error/helper text, character counter, etc.

* Option to set custom text for the floating label, where it will fall back to the default (getHint()) if none is provided.

I updated the test application and README, and can update the wiki in the main repo as well if necessary. You should give this a thorough test though, I can't think of any major edge cases that could cause problems with either, but that doesn't mean there aren't any.

![screenshot 2014-11-25 13 12 23](https://cloud.githubusercontent.com/assets/1361086/5194423/96bceabe-74c1-11e4-9539-758429265903.png)

![screenshot 2014-11-25 13 28 17](https://cloud.githubusercontent.com/assets/1361086/5194424/96cf93bc-74c1-11e4-81d9-e6ab72267a27.png)