Fix utf8 truncated output (#53)

* add --no-trunc to docker history command to prevent unwanted utf8 output

* add --no-trunc to docker history command to prevent unwanted utf8 output

Author: aschmidt75

controls/container_images.rb

@@ -178,7 +178,7 @@
   ref 'caching and apt-get update', url: 'https://github.com/moby/moby/issues/3313'
 
   docker.images.ids.each do |id|
-    describe command("docker history #{id}| grep -e 'update'") do
+    describe command("docker --no-trunc history #{id}| grep -e 'update'") do
       its('stdout') { should eq '' }
     end
   end
@@ -220,7 +220,7 @@
   ref 'Best practices for writing Dockerfiles', url: 'https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-practices/'
 
   docker.images.ids.each do |id|
-    describe command("docker history #{id}| grep 'ADD'") do
+    describe command("docker --no-trunc history #{id}| grep 'ADD'") do
       its('stdout') { should eq '' }
     end
   end