add pdf viewer and test doemal

Gemfile.lock

@@ -125,6 +125,7 @@ GEM
       thor (>= 0.14, < 2.0)
     jquery-ui-rails (6.0.1)
       railties (>= 3.2.16)
+    json (2.1.0)
     kaminari (1.0.1)
       activesupport (>= 4.1.0)
       kaminari-actionview (= 1.0.1)
@@ -168,6 +169,10 @@ GEM
     nokogiri (1.8.1)
       mini_portile2 (~> 2.3.0)
     pdf-core (0.7.0)
+    pdfjs_viewer-rails (0.2.0)
+      json (> 1.8.4)
+      rails (> 4.2.0)
+      sass-rails (~> 5.0)
     pg (0.21.0)
     prawn (2.2.2)
       pdf-core (~> 0.7.0)
@@ -333,6 +338,7 @@ DEPENDENCIES
   momentjs-rails
   mysql2 (>= 0.3.18, < 0.5)
   nested_form
+  pdfjs_viewer-rails
   pg
   prawn
   prawn-table