add RIETextArea - fixes #4

[devvmh]

I'm really interested in using this library with a textarea component in a project I'm working on, so am open to doing whatever to get this merged.

Textareas are the same as an input, with 3 differences:

1. Hitting Enter adds a newline, rather than calling stopEditing
2. The span displaying the results converts newlines into br tags
3. Textareas accept rows & cols as a property.

[devvmh]

@kaivi thoughts on merging? This has been working for me in production and I'd love to get the git url out of my package.json. Thanks! Whenever you get a chance it would be great!

[kaivi]

Thank you, I have now merged and uploaded a new version to NPM