[thrift] fix Ruby codegen: capitalize module name for enums

[thrift] fix Ruby codegen: capitalize module name for enums

Summary: all module names must be capitalized in Ruby -- if the enum name from the interface isn't capitalized \
         then it's a runtime error, e.g. in fb303_types.rb:

         -module fb_status
         +module Fb_status

Reviewed By: mcslee

Test Plan: fb303 now works with Ruby binding

Revert: OK

TracCamp Project: Thrift

DiffCamp Revision: 692

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@665288 13f79535-47bb-0310-9956-ffa450edef68