fixes #3140 - API to allow importing of puppet classes

works for v1 and v2

API URL examples

api/smart_proxies/7/import_puppetclasses
api/smart_proxies/7/import_puppetclasses?dryrun

api/smart_proxies/7/environments/15/import_puppetclasses
api/smart_proxies/7/environments/15/import_puppetclasses?dryrun

api/environments/15/smart_proxies/7/import_puppetclasses
api/environments/15/smart_proxies/7/import_puppetclasses?dryrun