Fix sizing of avatar circles; add border

* Adds border to group and project avatars
* Fixes cut-off circles
![Screen_Shot_2016-12-20_at_8.25.12_AM](/uploads/24e0eedf001f230300a316c504af59d4/Screen_Shot_2016-12-20_at_8.25.12_AM.png)
![Screen_Shot_2016-12-20_at_8.24.59_AM](/uploads/23450bf1f99b8075a043dd5512185e91/Screen_Shot_2016-12-20_at_8.24.59_AM.png)
Closes #25733

See merge request !8194