Add a small margin to reshares in bootstrap streams

I just moved the border to be on the .reshare, to avoid it to be collapsed next to the content (user photo).

**Before**
![before](https://cloud.githubusercontent.com/assets/930064/4530648/b4acfa0c-4d82-11e4-89c1-90e10f90d0b5.png)

**After**
![after](https://cloud.githubusercontent.com/assets/930064/4530647/b4a24f76-4d82-11e4-8bc7-d5ad8d3b457e.png)