fix(dialog): dialog now appears correctly

The CSS for modals in bootstrap 3 has
 
```css
display:hidden
```
by default - this patch makes sure that `display:block` is applied.

Is this a good approach? 

Also, what would the appropriate test be? Because there is no way to include the default bootstrap css in a karma test, the original test fail to detect the bug... (even though it does test for display:block)