Fix notification link color
Fix notification link color

Closes #772
- Changed notification link color inherit, and added underline

kevinansfield/Ghost-Admin,kevinansfield/Ghost-Admin,airycanon/Ghost-Admin,dbalders/Ghost-Admin,TryGhost/Ghost-Admin,TryGhost/Ghost-Admin,JohnONolan/Ghost-Admin,JohnONolan/Ghost-Admin,airycanon/Ghost-Admin,acburdine/Ghost-Admin,dbalders/Ghost-Admin,acburdine/Ghost-Admin