Ensure Rack::UTF8 Sanitizer is first middleware

If you set config.force_ssl=true in the rails app, it inserts the ActionDispatch::SSL middleware before Rack::Runtime. ActionDispatch::SSL also suffers from the utf8 issue. If we do config.middleware.insert 0, this ensures Rack::UTF8Sanitizer is at the top of the stack.
Merge pull request #13 from aaronrenner/patch-1

Ensure Rack::UTF8 Sanitizer is first middleware