Display opened github issues in user profile page

This adds a "Outside contributions" tab to the user profile page. After
clicking on it, it should show the user's Github contributions. But as
for the moment, it only shows the opened issues.

This requires that the user first add his/her github account information
in the user settings page.
16 jobs for feature/13401-display-opened-github-issues in 432 minutes and 48 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Test
passed #1380567
brakeman

00:11:24

passed #1380570
db-migrate-reset

00:14:22

passed #1380569
flay

00:11:09

passed #1380568
flog

00:11:13

passed #1380565
rubocop

00:09:54

passed #1380566
scss-lint

00:09:02

passed #1380556
spec:api

00:30:53

passed #1380555
spec:feature

00:55:39

passed #1380558
spec:lib

00:27:18

passed #1380557
spec:models

00:36:13

passed #1380560
spec:other

00:30:31

passed #1380559
spec:services

00:49:30

passed #1380563
spinach:other

00:35:04

passed #1380561
spinach:project:half

00:46:14

passed #1380562
spinach:project:rest

00:38:52

passed #1380564
teaspoon

00:15:21