Use theme's list separator color instead of a hard-coded value for the default changelog row

The current hard-coded color for the changelog row list separator doesn't look very nice in the Holo Dark theme:

![device-2014-06-21-213649](https://cloud.githubusercontent.com/assets/42659/3349691/73686f30-f973-11e3-923a-489b78737a44.png)

I think it looks better if we use the theme's list separator color:

![device-2014-06-21-213309](https://cloud.githubusercontent.com/assets/42659/3349687/28f13748-f973-11e3-9883-9e93317c87b4.png)