Cody Weaver 5db5057aaf
[BottomNavigation] Change badge position (#5339)
<h4>

```diff
- Warning - This may break screenshot testing -
```
</h4>

### Context
Currently the badge is centered on the top of the `iconImageView`. The `iconImageView`'s  `origin.y` is at 8.883 in MDC because we vertically center the _content_ in the MDCBottomNavigationItemView. We get the _content_ height by:

_contentHeight_ = icon.height + label.height + contentVerticalMargin

_contentVerticalMargin_ is the spacing between the icon and label.

The **_badge_** is 14dp tall. Centering the badge on the `iconImageView`'s `origin.y` puts the badge at 1.883.
### The problem
The badge is too high in relation to the top of the bottom navigation bar and doesn't match internal guidance.
### The fix
Make the badge and iconImageView have the same origin y, giving users more separation between the top of the navigation bar and the top of the badge.
### Related PR
Closes #4731 
### Screenshots
| Before | After |
| - | - |
|![simulator screen shot - iphone x - 2018-10-06 at 11 10 04](https://user-images.githubusercontent.com/7131294/46572709-65fa2f00-c958-11e8-8f57-5c0d389ae7c0.png)|![simulator screen shot - iphone x - 2018-10-06 at 11 09 29](https://user-images.githubusercontent.com/7131294/46572711-698db600-c958-11e8-838e-ee6ec31c7c50.png)|
2018-10-09 16:09:15 -04:00
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