B #3751: validate by APP_ENV (#4015)

Signed-off-by: Jorge Lobo <jlobo@opennebula.systems>
(cherry picked from commit f141633)

src/sunstone/sunstone-server.rb

@@ -152,6 +152,19 @@
     ENV['NO_PROXY'] = no_proxy
 end
 
+if ENV["APP_ENV"] && 
+    !ENV["APP_ENV"].empty? && 
+    %w{production development test}.include?(ENV["APP_ENV"])
+    set :environment, ENV["APP_ENV"].to_sym
+else
+    case $conf[:env]
+    when "dev"
+        set :environment, :development
+    else
+        set :environment, :production
+    end
+end
+
 case $conf[:sessions]
 when 'memory', nil
     use Rack::Session::Pool, :key => 'sunstone'