Show creation date of transaction

It would be very helpful for users to see a transaction's time of creation in this screen: [image](https://user-images.githubusercontent.com/763536/40410244-936fb988-5e6d-11e8-9a22-5edd9d14f594.png)

After logging in to metamask I'm sometimes confronted with a transaction and its hard to decide if it is an old one or the one I have created just before.

Start by locating the transaction screen shown in the linked image and tracing how transaction details are displayed after login. Add a visible creation time that lets users distinguish an older transaction from one created just before, then verify the screen shows the intended transaction date.

Written by the indexing model from the issue text.