Improve idempotency with respect to sysctl config file

Two bugs fixed:

- If sysctl value was already set to desired value, config file would not be
  updated.  This patch ensures idempotency of the config file.
- sysctl_param provider would not create state file if
  node["sysctl"]["params"] was undefined or empty
Remove unnecessary (and dangerous) node.save calls
merge Gemfile and README.md conflicts from master
updated Berkshelf, Rubocop and added lwrp and attribute test suites
Merge branch 'zendesk-master'