Fix erikhuda/thor#587

[hugocorbucci]

🌈
I bumped into the same issue @AlexandrZ in #587 had so I figured out the issue.
Problem showed itself as:

      create  bin/user_accounts
      chmod  bin/%microservice_name%
/ruby-2.4.2/lib/ruby/2.4.0/fileutils.rb:1241:in `chmod': No such file or directory @ chmod_internal - /user_accounts/bin/%microservice_name% (Errno::ENOENT)

That is, when copying a file that had a templated name with preserve mode, the path passed to the chmod command was of the original file instead of the interpreted one.

Added the spec to show the problem and the simple fix.
Let me know if you need anything else.