[webui] Enable web-console as debugging tool in the default error page

src/api/Gemfile

@@ -96,6 +96,8 @@ group :development do
   gem 'rack-mini-profiler'
   # for calling single testd
   gem 'single_test'
+  # as debugging tool in the default error page
+  gem 'web-console', '~> 2.0'
 end
 
 # Gems used only for assets and not required in production environments by default.

src/api/Gemfile.lock

@@ -40,6 +40,8 @@ GEM
       activerecord (>= 3.0)
     addressable (2.3.6)
     arel (6.0.0)
+    binding_of_caller (0.7.2)
+      debug_inspector (>= 0.0.1)
     builder (3.2.2)
     capybara (2.4.4)
       mime-types (>= 1.16)
@@ -67,6 +69,7 @@ GEM
     daemons (1.1.9)
     dalli (2.7.2)
     database_cleaner (1.3.0)
+    debug_inspector (0.0.2)
     delayed_job (4.0.6)
       activesupport (>= 3.0, < 5.0)
     delayed_job_active_record (4.0.3)
@@ -226,6 +229,11 @@ GEM
     unicorn-rails (2.2.0)
       rack
       unicorn
+    web-console (2.0.0)
+      activemodel (~> 4.0)
+      binding_of_caller (>= 0.7.2)
+      railties (~> 4.0)
+      sprockets-rails (>= 2.0, < 4.0)
     webmock (1.19.0)
       addressable (>= 2.3.6)
       crack (>= 0.3.2)
@@ -286,6 +294,7 @@ DEPENDENCIES
   timecop
   uglifier (>= 1.2.2)
   unicorn-rails
+  web-console (~> 2.0)
   webmock (>= 1.18.0)
   xmlhash (>= 1.3.6)
   yajl-ruby