Update style of snippets pages

Replaces !1567 (closed).

Fixes #1767 (closed) and #2538 (closed).

mentioned in merge request !1567 (closed)

Added 1 commit:

• 44df2012 - Restore dashboard snippets tabs.

Reassigned to @dzaporozhets

Added 1 commit:

• d9944fdb - Fix spec

@DouweM can you make it look like this - https://gitlab.com/gitlab-org/gitlab-ce/issues/2538 ?

Reassigned to @DouweM

@dzaporozhets Good one! Will change the tabs asap.

Added 144 commits:

• d9944fdb...35618a3d - 142 commits from branch master
• d37cf642 - Merge branch 'master' into hanloong/gitlab-ce-add-dates-snippets-show
• de9886be - Restyle dashboard snippets visibility level tabs.

@dzaporozhets Updated, screenshot in issue description.

Reassigned to @dzaporozhets

@DouweM thanks

Added 1 commit:

• c7c5bd48 - 1 commit from branch master

Status changed to merged

mentioned in commit 01315cfe

Does this fix #3091 (closed)

@rschilling I don't think it does, I didn't touch the new/edit snippet page at all.