RestService Code Cleanup

RestService would benefit from a refactor that cleans up the code and clearly defines methods in RequestParser/RequestValidator to adhere to the purpose defined by the class name: i.e. request parsing occurs in some methods in request validator and requestparser only parses URL content, not the full request.

Some work was done in #727 to begin cleanup.

Review RestService, RequestParser, and RequestValidator, then compare their current responsibilities with the cleanup started in issue #727. Trace which methods perform request parsing versus URL parsing and define completion as each class adhering to the purpose described in this issue.

Written by the indexing model from the issue text.