Touch project when toggling stars to update cache

This is a fix for gitlab-org/gitlab-ce#3513.

When a star toggle event happens, we touch project to clear cache key. This will trigger a new "updated_at" at the project model. If it's undesirable, please let me know and I will try to solve it in a different way.

mentioned in merge request !1939 (closed)

Added 50 commits:

• 64a6bce1...ca7e31c4 - 49 commits from branch master
• ceb12580 - Add touch to project when toggling stars to update cache

Can we do this using touch: true on the relation that currently has the counter_cache: :star_count?

👍 for @DouweM suggestion

Added 1 commit:

• 9e584702 - Touch project when toggling stars to update cache

Added 36 commits:

• 9e584702...76f00542 - 35 commits from branch master
• 82e916b0 - Touch project when toggling stars to update cache

@dzaporozhets done! All 💚

Reassigned to @dzaporozhets

@brodock awesome! Thank you

mentioned in commit 15ea1285

Status changed to merged

mentioned in commit e7a8fe07

mentioned in commit tnir/gitlab-ce@fa854474

mentioned in commit maxraab/gitlab-ce@ea13df6d