Update rubocop/TK base configs, add elkstack

- Add platformstack defaults on .kitchen.yml in case it is ever included
- Update to latest .rubocop.yml from templatestack
- Add elkstack to berksfile and dependency in metadata
- Lint work on unit tests
logic bomb in unit test, was missing assignment
Add proper PATH variables for new serverspec v2
Set backend appropriately for new serverspec v2
Back out on elkstack stuff for now
More serverspec v2 fixes
Remove errant whitespace
Merge pull request #235 from martinb3/fix_serverspec2

Fix serverspec2