Update the json gem to >=2 which allows a top-level scalar value as JSON

Gemfile

@@ -108,7 +108,7 @@ gem 'httparty', '~> 0.13'
 gem 'httmultiparty', '~> 0.3.16'
 gem 'jquery-rails', '~> 4.2.1'
 gem 'huginn_agent', '~> 0.4.0'
-gem 'json', '~> 1.8.1'
+gem 'json', '~> 2.3'
 gem 'jsonpath', '~> 1.0.1'
 gem 'kaminari', '~> 1.1.1'
 gem 'kramdown', '~> 1.3.3'

Gemfile.lock

@@ -345,7 +345,7 @@ GEM
       rails-dom-testing (>= 1, < 3)
       railties (>= 4.2.0)
       thor (>= 0.14, < 2.0)
-    json (1.8.6)
+    json (2.3.0)
     jsonpath (1.0.1)
       multi_json
       to_regexp (~> 0.2.1)
@@ -706,7 +706,7 @@ DEPENDENCIES
   huginn_agent (~> 0.4.0)
   hypdf (~> 1.0.10)
   jquery-rails (~> 4.2.1)
-  json (~> 1.8.1)
+  json (~> 2.3)
   jsonpath (~> 1.0.1)
   kaminari (~> 1.1.1)
   kramdown (~> 1.3.3)