ceil @input-height-large calculation

This is the current @input-height-large calculation:

```less
@input-height-large: (floor(@font-size-large * @line-height-large) + (@padding-large-vertical * 2) + 2);
```

or

```less
@input-height-large: (floor(18 * 1.33) + (10 * 2) + 2);
```

I've noticed that:
18 * 1.31 = 23.58
18 * 1.3 = 23.4

I've been looking for #10936 and I've noticed that when ```.input-group-addon``` line-height is 1.30 it looks fine, but when line-height is 1.31 it break on FF 24 OSX.

Maybe FF rounds up line-height, so I think is safer to round this value up with ceil.

I hope this fix #10936 and #10482. I've tested on FF 24 OSX and it works fine.