Remove the -h option to dbconsole which is the shorter form of --header

This is done since the -h option to dbconsole hides the conventional
-h for help and forces users to use --help to see the usage options for
dbconsole.

railties/lib/rails/commands/dbconsole.rb

@@ -33,7 +33,7 @@ module Rails
             options['mode'] = mode
         end
 
-        opt.on("-h", "--header") do |h|
+        opt.on("--header") do |h|
           options['header'] = h
         end