Disable noisy/unneeded puppet-lint checks

* disable '80 characters check' - this is pretty useless and noisy
* disable 'class inherits from params class' check - is for puppet 2.6 which isn't supported
* disable 'only variable string check' - currently required by puppetlabs-concat
Fix remaining lint warnings
Fail on lint warnings from now on

Should improve PR quality and eliminate need for PRs to fix
any future lint issues