Removed unused Manifest arguments
Code tidy: put object above trait
JsonConfig: changed String path arguments to JPaths
Problem: added proxy methods for JsonConfig.{get,set,remove}
Reimplemented StringValidation
Updated RedisSessionActions to new-style Problems
Updates to toClientProblem and toServerProblem

 - Switched to more natural type class style use
 - Added new type alias: type ProblemValidation[T] = Validation[Problem, T]
 - Return ProblemValidations rather than FutureValidations
Remove unused Manifest arguments
Update SessionServices to new-style to{Client,Server}Problem
Removed unused Manifest arguments
Updated rest of Bigtop to new-style to{Client,Server}Problem; removed conflicting JsonValidation type alias from UserTypes