Refactor link_box to make better use of bootstrap

- rework the css that I wrote a year ago to look nicer
- remove some of the "hacky" solutions that I wrote

Closes #114
4 jobs for 114-link-box-mobile-fix in 1 minute and 43 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #2685
Go-py2.7

00:01:41

passed #2686
Go-py3.4

00:01:43

passed #2687
Go-py3.5

00:01:41

passed #2688
Go-py3.6

00:01:43