Bump jbuilder from 2.7.0 to 2.8.0 (#622)

Bumps [jbuilder](https://github.com/rails/jbuilder) from 2.7.0 to 2.8.0.
- [Release notes](https://github.com/rails/jbuilder/releases)
- [Changelog](https://github.com/rails/jbuilder/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rails/jbuilder/commits)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Gemfile.lock

@@ -125,7 +125,7 @@ GEM
       coffee-script-source
       execjs
     coffee-script-source (1.12.2)
-    concurrent-ruby (1.0.5)
+    concurrent-ruby (1.1.1)
     connection_pool (2.2.2)
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
@@ -197,7 +197,7 @@ GEM
       concurrent-ruby (~> 1.0)
     io-like (0.3.0)
     jaro_winkler (1.5.1)
-    jbuilder (2.7.0)
+    jbuilder (2.8.0)
       activesupport (>= 4.2.0)
       multi_json (>= 1.2)
     jquery-rails (4.3.3)