win_regedit integration test to cover change to allow empty string comparison

[jhawkesworth]

ISSUE TYPE

• Bugfix Pull Request

ANSIBLE VERSION

ansible 2.1.0 (devel ba74f5f3e5) last updated 2016/04/20 23:46:56 (GMT +100)
  lib/ansible/modules/core: (devel 36755e5fe2) last updated 2016/04/24 16:06:03 (GMT +100)
  lib/ansible/modules/extras: (devel de22b721db) last updated 2016/04/24 16:03:40 (GMT +100)
  config file = /etc/ansible/ansible.cfg
  configured module search path = Default w/o overrides

SUMMARY

Add integration test to ensure empty strings, which are legitimate registry data entry values to be compared.

See the conversation on ansible/ansible-modules-extras#2034 for background.

Test covers the fix in ansible/ansible-modules-extras@7d9b73e (which was accidentally pushed straight to devel instead of via a PR

n/a only affects integration test output for make test_winrm -t test_win_regedit