Fixed case for Fn-headers according to the container contract

Added Fn-Fdk-Version header to response

Author: Gaurav Saini

lib/fdk/context.rb

@@ -51,6 +51,7 @@ def each(&block)
   # Represents outbound HTTP headers
   class OutHeaders < InHeaders
     def initialize(headers, key_in_fn)
+      headers["Fn-Fdk-Version"] = ["fdk-ruby/#{FDK::VERSION}"]
       super(headers, key_in_fn)
     end