Change closes buttons to &times; instead the letter 'X'

Hi,

I think that the unicode &times; is most "consistent" to use instead the letter X. What do you think?

Using the letter "X";
![](http://f.cl.ly/items/09320M2E001d1l1e1S1y/Screen%20Shot%202014-09-22%20at%2011.49.37.png)

Using the &times; unicode
![](http://f.cl.ly/items/3z3A2a3h3u3e2q30003M/Screen%20Shot%202014-09-22%20at%2011.50.05.png)

:smile_cat: