Improve README/Instances section

Make sure README undoubtably states that at least one instance
needs to be defined in order for service to start.
[TESTING] Switch to latest ES release
[TESTING] Switch to release beaker gem
Merge pull request #157 from electrical/testing_changes

Testing changes
[Feature] Add proxy options to plugin define

This allows to make use of a Proxy server for installation of plugins.
This will work for http and https sites.
Merge pull request #156 from igoraj/master

Improve README/Instances section
Update readme for proxy feature
[TESTING] Improve different parts of the acceptance testing

- Move all variables into a single file
- Make packages more dynamic per distro and version
Merge pull request #161 from electrical/refactor_testing

[TESTING] Improve different parts of the acceptance testing
[TESTING] Fix correct package version
Merge pull request #162 from electrical/master

[TESTING] Fix correct package version
[TESTING] more fixes for correct version
Merge pull request #163 from electrical/master

[TESTING] more fixes for correct version
[TESTING] Forgot 2 more version numbers
Merge pull request #164 from electrical/master

[TESTING] Forgot 2 more version numbers
Merge pull request #158 from electrical/plugin_proxy

[Feature] Add proxy options to plugin define
Fix Instance define

- Ensure and Status were not passed on correct
- When removing a single instance it failed

Closes #166
Merge pull request #167 from electrical/master

Fix Instance define
Fix Systemd service manager

Systemd was failing with the new tests.
Refactored sequencing.
Merge pull request #169 from electrical/fix_systemd

Fix Systemd service manager