#5537 - Fix bulk edit overlap, bulkedit improvements

Fixes overlap reported in #5537. Before - http://cld.wthms.co/EAKA

**Now:**

![see screen shot](http://cld.wthms.co/10PUa+)

**Several other minor improvements (didn't warrant another PR):**
* Add currency symbol in placeholder for price/sale price
* Add weight unit in placeholder for weight
* Add dimensions unit in placeholder for width/length/height
* Change input type for Stock Quantity to text, as WC supports fractional stock amounts now