[json_file] drop monkey patch json_file resource, use a lwrp
[json_file] module methods
[json_file] sensu_json_file library, don't conflict w/ lwrp generated class
[json_file] no need to use ::File in lwrps
Merge pull request #119 from portertech/json_file

Replace json_file resource monkey patching with sensu_json_file LWRP