Enable parsing json format body when content type has '+json' suffix.

[doyaaaaaken]

HI. When I send request which has application/scim+json value on content-type, the request body is not shown on access logs page. This problem is caused by body parsing logic. Existing logic only allows application/json' and application/vnd.api+json.

Mime type value which has +json suffix is allowed on (RFC6838)[https://tools.ietf.org/html/bcp13#section-4.2.8]. So, I think .*+json content-type request body should be also parsed.