Admin: Clip the first and last Ophan pageview entries

Fixes this:

**Before:**
![ophan-before](https://f.cloud.github.com/assets/518943/1116195/af8cf840-1a36-11e3-8da3-ff1cdc1c18e4.png)

**After:**
![ophan-after](https://f.cloud.github.com/assets/518943/1116196/b0c72eba-1a36-11e3-9ae5-06ffd45e5b8d.png)