Added watermark while input is focused. 

- Displaying watermark text as long as no input was made, just like the
implementation of watermarks in new browsers. (Above screenshot is from an IE7.)
![input_watermark](https://f.cloud.github.com/assets/1503577/177681/9266c5c6-7b9d-11e2-9dbb-26fb2b90fedf.png)

- Added example html file.