item description menu: show weight units right after the value

subj.

was:
![was](https://f.cloud.github.com/assets/5421954/1786799/0d54d106-68fb-11e3-9d4b-bf00f688ea36.png)


is:
![is](https://f.cloud.github.com/assets/5421954/1786800/10b1b594-68fb-11e3-998f-4255907c8ba0.png)