[BUGFIX] read_gist to behave like api

Author: Rajasegar

Diff for: bin/gist

@@ -173,7 +173,8 @@ begin
 
   if options.key? :read
     file_name = ARGV.first
-    Gist.read_gist(options[:read], file_name)
+    output = Gist.read_gist(options[:read], file_name)
+    puts output if output
     exit
   end
 

Diff for: lib/gist.rb

@@ -236,7 +236,7 @@ def read_gist(id, file_name=nil)
         file = files.values.first
       end
 
-      puts file["content"]
+      file["content"]
     else
       raise Error, "Gist with id of #{id} does not exist."
     end